Multilayer ceramic capacitor

ABSTRACT

A multilayer ceramic capacitor includes, in at least one of a region between an end of a first internal electrode layer which is not connected to a second external electrode and the second external electrode, and a region between an end of a second internal electrode layer which is not connected to a first external electrode and the first external electrode, in a length direction, a defect portion provided on a plane including a stacking direction and a width direction, such that the defect portion is located between the first dielectric ceramic layers in the stacking direction and is located between the second dielectric ceramic layer and the third dielectric ceramic layer in the width direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2019-238184 filed on Dec. 27, 2019 and Japanese PatentApplication No. 2020-186019 filed on Nov. 6, 2020. The entire contentsof these applications are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a multilayer ceramic capacitor.

2. Description of the Related Art

In recent years, multilayer ceramic electronic components, such asmultilayer ceramic capacitors, have been miniaturized and developed togenerate higher capacitance. To achieve miniaturization and highercapacitance of the multilayer ceramic capacitors, it is advantageous toreduce the thickness of the side margin with respect to each sidesurface of a multilayer body in which a plurality of dielectric ceramiclayers and a plurality of internal electrode layers are stacked, therebyincreasing the area of the internal electrode layers provided oppositeto each other.

Japanese Unexamined Patent Application, Publication No. 2017-147358discloses a method for manufacturing an electronic component including astep of preparing a chip in which a plurality of dielectric ceramiclayers and a plurality of internal electrode layers are stacked, theplurality of internal electrode layers being exposed on a side surface,a step of pasting a plurality of covering dielectric sheets to eachother to form a dielectric laminated sheet, and a step of applying thedielectric laminated sheet on a side surface of the chip.

Furthermore, Japanese Unexamined Patent Application, Publication No.2003-209025 discloses that a plurality of ceramic green sheets eachhaving internal electrodes printed therein is stacked, and ceramicslurry for level difference elimination is applied in an area in whichinternal electrodes are not printed when pressurizing and firing toproduce a multilayer ceramic capacitor, whereby it is possible tosuppress the level difference generated between a portion in which theinternal electrodes overlap with each other and a portion in which theinternal electrodes do not overlap with each other.

However, Japanese Unexamined Patent Application, Publication No.2017-147358 does not specifically describe the composition of a ceramicdielectric sheet to be bonded to the side surface of the multilayerbody. Japanese Unexamined Patent Application, Publication No.2003-209025 does not specifically describe the composition of a ceramicpaste for level difference elimination used in Japanese UnexaminedPatent Application, Publication No. 2003-209025. Therefore, in JapaneseUnexamined Patent Application, Publication No. 2017-147358 and JapaneseUnexamined Patent Application, Publication No. 2003-209025, there isroom to improve the reliability of multilayer ceramic capacitors byoptimizing the composition of the dielectric laminated sheet and thecomposition of the ceramic paste for level difference elimination.Furthermore, as in a case of the dielectric ceramic layer with a ceramicslurry for level difference elimination disclosed in Japanese UnexaminedPatent Application, Publication No. 2003-209025, in the case ofincluding a dielectric ceramic layer different from the dielectricceramic layer disposed between internal electrode layers to be stacked,cracks or chips may occur in the dielectric ceramic layer due to stressgenerated during firing.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide multilayerceramic capacitors that are each capable of reducing or preventing theoccurrence of cracks and chips at least in a dielectric ceramic layerfor level difference elimination due to a stress generated duringfiring.

A multilayer ceramic capacitor according to a preferred embodiment ofthe present invention includes a multilayer body including a dielectricceramic layer and an internal electrode layer stacked in a stackingdirection; and an external electrode connected to the internal electrodelayer; wherein the multilayer body includes a first main surface and asecond main surface on opposite sides in the stacking direction, a firstside surface and a second side surface on opposite sides in a widthdirection orthogonal or substantially orthogonal to the stackingdirection, and a first end surface and a second end surface on oppositesides in a length direction orthogonal or substantially orthogonal tothe stacking direction and the width direction; the internal electrodelayer includes a first internal electrode layer that extends to thefirst end surface, and a second internal electrode layer that extends tothe second end surface; the second internal electrode layer is opposedto the first internal electrode layer with the dielectric ceramic layerinterposed therebetween; the external electrode includes a firstexternal electrode that is disposed on the first end surface and isconnected to the first internal electrode layer, and a second externalelectrode that is disposed on the second end surface and is connected tothe second internal electrode layer; the dielectric ceramic layerincludes a first dielectric ceramic layer and a second dielectricceramic layer; the first dielectric ceramic layer is disposed betweenthe first internal electrode layer and the second internal electrodelayer; the second dielectric ceramic layer includes a region between thefirst dielectric ceramic layers opposite to each other with the internalelectrode layer interposed therebetween, and in which the internalelectrode layer is not disposed, and such that a portion of the seconddielectric ceramic layer overlaps the first dielectric ceramic layer inthe stacking direction; the multilayer body includes an inner layerportion in which the first internal electrode layer and the secondinternal electrode layer are alternately stacked with the dielectricceramic layer interposed therebetween, an outer layer portionsandwiching the inner layer portion in the stacking direction andincluding a ceramic material, and a third dielectric ceramic layersandwiching the inner layer portion and the outer layer portion in thewidth direction and including a dielectric ceramic material; and in atleast one of a region between an end of the first internal electrodelayer which is not connected to the second external electrode and thesecond external electrode, and a region between an end of the secondinternal electrode layer which is not connected to the first externalelectrode and the first external electrode, in the length direction, adefect portion defined by a portion that is partially missing in thesecond dielectric ceramic layer is provided on a plane including thestacking direction and the width direction, such that the defect portionis located between the first dielectric ceramic layers in the stackingdirection and is located between the second dielectric ceramic layer andthe third dielectric ceramic layer in the width direction.

According to preferred embodiments of the present disclosure, it ispossible to provide multilayer ceramic capacitors that are each able toreduce or prevent an occurrence of cracks and chips in a dielectricceramic layer for level difference elimination due to a stress generatedduring firing.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing an example of amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention.

FIG. 2 is a perspective view schematically showing an example of amultilayer body included in the multilayer ceramic capacitor shown inFIG. 1.

FIG. 3 is a sectional view taken along line A-A of the multilayerceramic capacitor shown in FIG. 1.

FIG. 4 is a sectional view taken along line C-C of the multilayerceramic capacitor shown in FIG. 1.

FIG. 5 is a sectional view taken along line B-B of the multilayerceramic capacitor shown in FIG. 1.

FIG. 6 is a plan view schematically showing an example of a ceramicgreen sheet.

FIG. 7 is a plan view schematically showing an example of a ceramicgreen sheet.

FIG. 8 is a plan view schematically showing an example of a ceramicgreen sheet.

FIG. 9 is an exploded perspective view schematically showing an exampleof a mother block.

FIG. 10 is a perspective view schematically showing an example of agreen chip.

FIG. 11 shows a portion of an LT cross-section of a multilayer ceramiccapacitor according to a preferred embodiment of the present invention,and is a diagram schematically showing a first alloy portion and asecond alloy portion.

FIG. 12 is a partially enlarged view of FIG. 11.

FIG. 13 shows a portion of an LT cross-section of a multilayer ceramiccapacitor according to a preferred embodiment of the present invention,and is a diagram schematically showing a first interspersed internalelectrode, a second interspersed internal electrode, and a fourth alloyportion.

FIG. 14 shows a portion of a WT cross-section of a multilayer ceramiccapacitor according to a preferred embodiment of the present invention,and is a diagram schematically showing a first alloy portion and a thirdalloy portion.

FIG. 15 is a partially enlarged view of FIG. 14, and schematically showsa fifth alloy portion.

FIG. 16 shows a cross-sectional view schematically showing a mode inwhich an end of a second dielectric ceramic layer is superimposed on anend of an internal electrode layer in a multilayer ceramic capacitoraccording to a preferred embodiment of the present invention.

FIG. 17 shows a cross-sectional view schematically showing a mode inwhich the end of the second dielectric ceramic layer is superimposed onthe end of the internal electrode layer in a multilayer ceramiccapacitor according to a preferred embodiment of the present invention.

FIG. 18 is a diagram for explaining a TEM analysis method for analyzingthe amount of a metal element included in the internal electrode layerof a multilayer ceramic capacitor according to a preferred embodiment ofthe present invention.

FIG. 19 is a partial view of FIG. 5, and shows a near intersectionregion according to a preferred embodiment of the present invention.

FIG. 20 is a diagram for explaining a method for measuring the averageparticle size of dielectric particles included in a first dielectricceramic layer and a third dielectric ceramic layer.

FIG. 21 is a diagram for explaining a method for measuring the averageparticle size of the dielectric particles included in the thirddielectric ceramic layer.

FIG. 22 is a diagram for explaining a first stage of a method formeasuring the average particle size of the dielectric particles includedin the second dielectric ceramic layer and the near intersection region.

FIG. 23 is a diagram for explaining a second stage of a method formeasuring the average particle size of the dielectric particles includedin the second dielectric ceramic layer and the near intersection region.

FIG. 24 is a diagram for explaining a method for measuring the averageparticle size of the dielectric particles included in the nearintersection region.

FIG. 25 is a diagram schematically showing a step of removing a sidesurface of an unfired multilayer body in a method for manufacturing amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention.

FIG. 26 is a diagram showing an end surface of an unfired multilayerbody in which a side surface is removed in a method for manufacturing amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention.

FIG. 27 is a cross-sectional view schematically showing a mode in whichan end of the second dielectric ceramic layer is superimposed on an endof the internal electrode layer in a method for manufacturing amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention.

FIG. 28 shows a portion of a WT cross-section of a multilayer ceramiccapacitor according to a preferred embodiment of the present invention,and is a diagram schematically showing a defect portion of the seconddielectric ceramic layer.

FIG. 29 is a cross-sectional view taken along line K-K in FIG. 28.

FIG. 30 shows a portion of a LT cross-section of a multilayer ceramiccapacitor according to a preferred embodiment of the present invention,and is a diagram schematically showing a first segregation.

FIG. 31 is a partially enlarged view of FIG. 30.

FIG. 32 shows a portion of a WT cross-section of a multilayer ceramiccapacitor according to a preferred embodiment of the present invention,and is a diagram schematically showing a second segregation.

FIG. 33 shows a portion of a LW cross-section of a multilayer ceramiccapacitor according to a preferred embodiment of the present invention,and is a diagram showing a third segregation which segregates in a firstcorner region and a second corner region.

FIG. 34 is a cross-sectional view schematically showing a mode in whichan end of the second dielectric ceramic layer is superimposed on thethird segregation in a multilayer ceramic capacitor according to apreferred embodiment of the present invention.

FIG. 35 is a diagram showing the thickness of the first dielectricceramic layer at the central portion in the length (L) direction of amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention.

FIG. 36 is a diagram showing the thickness of the second dielectricceramic layer of a multilayer ceramic capacitor according to a preferredembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, multilayer ceramic capacitors according to preferredembodiments of the present invention will be described with reference tothe drawings. However, the present invention is not limited to thefollowing preferred embodiments, and can be applied by modifying whereappropriate within a scope not changing the gist of the presentinvention. It should be noted that preferred embodiments of the presentinvention also includes combinations of two or more of the individualpreferred embodiments described below.

Multilayer Ceramic Capacitor

FIG. 1 is a perspective view schematically showing an example of amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention. FIG. 2 is a perspective view schematically showing anexample of a multilayer body (for example, a laminate) included in themultilayer ceramic capacitor shown in FIG. 1. FIG. 3 is across-sectional view taken along line A-A of the multilayer ceramiccapacitor shown in FIG. 1. FIG. 4 is a cross-sectional view taken alongline C-C of the multilayer ceramic capacitor shown in FIG. 1.

In the present disclosure, a stacking direction (for example, laminationdirection), a width direction, and a length direction of the multilayerceramic capacitor and the multilayer body are respectively defined bythe arrows T, W, and L in the multilayer ceramic capacitor 1 shown inFIG. 1 and the multilayer body 10 shown in FIG. 2. Herein, the stacking(T) direction, the width (W) direction, and the length (L) direction areorthogonal or substantially orthogonal to one another. The stacking (T)direction refers to a direction in which a plurality of dielectricceramic layers 20, and a plurality of pairs of a first internalelectrode layer 21 and a second internal electrode layer 22 are stacked.

The multilayer ceramic capacitor 1 shown in FIG. 1 includes themultilayer body 10, and a first external electrode 51 and a secondexternal electrode 52 provided on both end surfaces of the multilayerbody 10, respectively.

As shown in FIG. 2, the multilayer body 10 has a rectangular shape or asubstantially rectangular shape. The multilayer body 10 includes a firstmain surface 11 and a second main surface 12 on opposite sides in thestacking (T) direction, a first side surface 13 and a second sidesurface 14 on opposite sides in the width (W) direction which isorthogonal or substantially orthogonal to the stacking (T) direction,and a first end surface 15 and a second end surface 16 on opposite sidesin the length (L) direction which is orthogonal or substantiallyorthogonal to the stacking (T) direction and the width (W) direction.

In the present disclosure, a cross-section of the multilayer ceramiccapacitor 1 or the multiplayer body 10 which is orthogonal orsubstantially orthogonal to the first end surface 15 and the second endsurface 16, and parallel or substantially parallel to the stacking (T)direction refers to the LT cross-section, which is a cross-section inthe length (L) direction and the stacking (T) direction. Furthermore, across-section of the multilayer ceramic capacitor 1 or the multiplayerbody 10 which is orthogonal or substantially orthogonal to the firstside surface 13 and the second side surface 14, and parallel orsubstantially parallel to the stacking (T) direction refers to WTcross-section, which is a cross-section in the width (W) direction andthe stacking (T) direction. Furthermore, a cross-section of themultilayer ceramic capacitor 1 or the multiplayer body 10 which isorthogonal or substantially orthogonal to the first side surface 13, thesecond side surface 14, the first end surface 15, and the second endsurface 16, and orthogonal or substantially orthogonal to the stacking(T) direction refers to LW cross-section, which is a cross-section inthe length (L) direction and the width (W) direction. Therefore, FIG. 3is an LT cross-section of the multilayer ceramic capacitor 1, and FIG. 4is a WT cross-section of the multilayer ceramic capacitor 1.

The multilayer body 10 preferably has rounded corners and ridges. Thecorners are portions where the three surfaces of the multilayer bodyintersect, and the ridges are portions where the two surfaces of themultilayer body intersect.

As shown in FIGS. 2, 3 and 4, the multilayer body 10 has a multilayerstructure including a plurality of dielectric ceramic layers 20 stackedin the stacking (T) direction, and a plurality of pairs of the firstinternal electrode layer 21 and the second internal electrode layer 22provided along the interface between the dielectric ceramic layers 20.The dielectric ceramic layer 20 extends along the width (W) directionand the length (L) direction, and each of the first internal electrodelayer 21 and the second internal electrode layer 22 extends in a flatplate shape along the dielectric ceramic layer 20.

The first internal electrode layer 21 extends to the first end surface15 of the multilayer body 10. On the other hand, the second internalelectrode layer 22 extends to the second end surface 16 of themultilayer body 10.

The first internal electrode layer 21 and the second internal electrodelayer 22 are provided opposite to each other with the dielectric ceramiclayer 20 interposed therebetween in the stacking (T) direction.Capacitance is generated by a portion where the first internal electrodelayer 21 and the second internal electrode layer 22 are providedopposite to each other with the dielectric ceramic layer 20 interposedtherebetween.

Each of the first internal electrode layer 21 and the second internalelectrode layer 22 preferably includes a metal such as Ni, Cu, Ag, Pd,or Au, or Ag—Pd alloy, for example. Each of the first internal electrodelayer 21 and the second internal electrode layer 22 may include the samedielectric ceramic material as that of the dielectric ceramic layer 20,in addition to the metal.

The dielectric ceramic layer 20 includes a first dielectric ceramiclayer 20 a, and a second dielectric ceramic layer 20 b. The firstdielectric ceramic layer 20 a is disposed between the first internalelectrode layer 21 and the second internal electrode layer 22. Thesecond dielectric ceramic layer 20 b is disposed in a region where theinternal electrode layers (21 and 22) are not disposed, between thefirst dielectric ceramic layers 20 a provided opposite to each otherwith the internal electrode layer (21 and 22) interposed therebetween.

The first external electrode 51 is provided on the first end surface 15of the multilayer body 10 and, in FIG. 1, includes a portion whichextends over a portion of each of the first main surface 11, the secondmain surface 12, the first side surface 13 and the second side surface14. The first external electrode 51 is connected to the first internalelectrode layer 21 at the first end surface 15.

The second external electrode 52 is provided on the second end surface16 of the multilayer body 10 and, in FIG. 1, includes a portion whichextends over a portion of each of the first main surface 11, the secondmain surface 12, the first side surface 13, and the second side surface14. The second external electrode 52 is connected to the second internalelectrode layer 22 at the second end surface 16.

Each of the first external electrode 51 and the second externalelectrode 52 preferably includes a Ni layer including Ni and a ceramicmaterial, for example. The Ni layer is a foundation electrode layer (forexample, base electrode layer). Such a Ni layer can be formed by acofiring method in which firing is performed simultaneously with thefirst internal electrode layer 21 and the second internal electrodelayer 22. The Ni layer is preferably disposed directly on the multilayerbody 10.

The first external electrode 51 preferably includes the Ni layer, afirst plated layer, and a second plated layer in order from a side ofthe first end surface 15 of the multilayer body 10. Similarly, thesecond external electrode 52 preferably includes the Ni layer, the firstplated layer, and the second plated layer in order from a side of thesecond end surface 16 of the multilayer body 10. The first plated layeris preferably formed by Ni plating, and the second plated layer ispreferably formed by Sn plating, for example. Each of the first externalelectrode 51 and the second external electrode 52 may include aconductive resin layer including conductive particles and a resinbetween the Ni layer and the first plated layer. Examples of theconductive particles in the conductive resin layer include metalparticles of Cu, Ag, and Ni.

It should be noted that the Ni layer may be formed by a so-calledpost-firing method which applies a conductive paste to the end surfaceof the multilayer body, and then performs firing. In this case, it maybe unnecessary for the Ni layer to contain a ceramic material.

Alternatively, each of the first external electrode 51 and the secondexternal electrode 52 may include a foundation electrode layer includinga metal such as Cu. The foundation electrode layer may be formed by acofiring method or a post-firing method. Furthermore, the foundationelectrode layer may include a plurality of layers.

For example, the first external electrode 51 may have a four-layerstructure including a Cu layer as a foundation electrode layer, aconductive resin layer including conductive particles and a resin, thefirst plated layer, and the second plated layer in order from a side ofthe first end surface 15 of the multilayer body 10. Similarly, thesecond external electrode 52 may have, for example, a four-layerstructure including a Cu layer as a foundation electrode layer, aconductive resin layer including conductive particles and resin, thefirst plated layer, and the second plated layer in order from a side ofthe second end surface 16 of the multilayer body 10.

As shown in FIGS. 3 and 4, the dielectric ceramic layer 20 includes thefirst dielectric ceramic layer 20 a and the second dielectric ceramiclayer 20 b. The first dielectric ceramic layer 20 a is disposed betweenthe first internal electrode layer 21 and the second internal electrodelayer 22. The second dielectric ceramic layer 20 b is disposed in aregion where the internal electrode layer is not disposed, between thefirst dielectric ceramic layers 20 a provided opposite to each otherwith the internal electrode layer interposed therebetween.

As shown in FIGS. 2, 3 and 4, the multilayer body 10 includes an innerlayer portion 30 in which the first internal electrode layer 21 and thesecond internal electrode layer 22 are provided opposite to each otherwith the dielectric ceramic layer 20 interposed therebetween, outerlayer portions 31 and 32 sandwiching the inner layer portion 30 in thestacking (T) direction, and a third dielectric ceramic layers 41 and 42sandwiching the inner layer portion 30, the outer layer portion 31, andthe outer layer portion 32 in the width (W) direction. Third dielectricceramic layers 41 and 42 are also referred to as side margin portions.In FIGS. 3 and 4, the inner layer portion 30 is a region sandwichedbetween the first internal electrode layer 21 closest to the first mainsurface 11 and the first internal electrode layer 21 closest to thesecond main surface 12 along the stacking (T) direction. Although notshown, each of the outer layer portion 31 and the outer layer portion 32preferably includes a plurality of dielectric ceramic layers 20 stackedin the stacking (T) direction, and more preferably includes the firstdielectric ceramic layer 20 a.

The thickness of each of the outer layer portions 31 and 32 ispreferably about 15 μm or more and about 40 μm or less, for example. Itshould be noted that each of the outer layer portions 31 and 32 may havea single layer structure rather than a multi-layered structure.

As shown in FIG. 4, each of the third dielectric ceramic layer 41 andthe third dielectric ceramic layer 42 may include a plurality ofdielectric ceramic layers stacked in the width (W) direction. Among theplurality of dielectric ceramic layers of the third dielectric ceramiclayers, the innermost layer in the width direction is referred to as aninner layer, and the outermost layer is referred to as an outer layer.The inner layer and the outer layer have an interface therebetween. InFIG. 4, the third dielectric ceramic layer 41 preferably has, as thedielectric ceramic layer, a two-layer structure including an inner layer41 a disposed innermost of the multilayer body 10, and an outer layer 41b disposed outermost of the multilayer body 10. Similarly, the thirddielectric ceramic layer 42 preferably has, as the dielectric ceramiclayer, a two-layer structure including an inner layer 42 a disposedinnermost of the multilayer body 10, and an outer layer 42 b disposedoutermost of the multilayer body 10. It should be noted that the thirddielectric ceramic layer is not limited to a two-layer structure, andmay have a structure including three or more layers. In a case in whichthe third dielectric ceramic layer includes three or more dielectricceramic layers, the dielectric ceramic layer disposed innermost in thewidth direction is the inner layer, and the dielectric ceramic layerdisposed outermost in the width direction is the outer layer.Furthermore, the number of layers of the third dielectric ceramic layerof the first side surface side of the multilayer body may be differentfrom that of the third dielectric ceramic layer of the second sidesurface side of the multilayer body.

In a case in which the third dielectric ceramic layer is a two-layerstructure including an inner layer and an outer layer, due to thedifference in sinterability in the inner layer and the outer layer, itis possible to confirm the two-layer structure and the interface betweenthe layers by observing with an optical microscope in a dark field. Thesame applies to a case where the third dielectric ceramic layer has astructure including three or more layers.

The first dielectric ceramic layer 20 a, the second dielectric ceramiclayer 20 b, and the third dielectric ceramic layers 41 and 42 are, forexample, made of a dielectric ceramic material mainly including BaTiO₃or the like. The dielectric ceramic layer 20 of the inner layer portion30 may further include a sintering aid element.

The dielectric ceramic layer of the first dielectric ceramic layer, thesecond dielectric ceramic layer, and the third dielectric ceramic layermay include ceramic grains. Details of the diameter of the ceramicgrains will be described later.

In the multilayer ceramic capacitor according to the present preferredembodiment, the composition of at least one dielectric ceramic layeramong the first dielectric ceramic layer, the second dielectric ceramiclayer, and the third dielectric ceramic layer is different from thecomposition of the other dielectric ceramic layers. The first dielectricceramic layer, the second dielectric ceramic layer, and the thirddielectric ceramic layer each have a different arrangement purpose ordifferent characteristics required for the manufacturing method.Therefore, by setting the composition of at least one dielectric ceramiclayer among the first dielectric ceramic layer, the second dielectricceramic layer, and the third dielectric ceramic layer to be differentfrom the composition of the other dielectric ceramic layers, it ispossible to achieve an optimum composition according to the locationwhere the dielectric ceramic layer is disposed, making it possible toincrease the reliability.

In the multilayer ceramic capacitor according to the present preferredembodiment, the composition of the first dielectric ceramic layer may bedifferent from the compositions of the second dielectric ceramic layerand the third dielectric ceramic layer, the composition of the seconddielectric ceramic layer may be different from the compositions of thefirst dielectric ceramic layer and the third dielectric ceramic layer,the composition of the third dielectric ceramic layer may be differentfrom the compositions of the first dielectric ceramic layer and thesecond dielectric ceramic layer, and the composition of the firstdielectric ceramic layer, the composition of the second dielectricceramic layer, and the composition of the third dielectric ceramic layermay be different from one another.

In the multilayer ceramic capacitor of the present preferred embodiment,the composition of the second dielectric ceramic layer and thecomposition of the third dielectric ceramic layer are preferablydifferent from each other, and the composition of the first dielectricceramic layer, the composition of the second dielectric ceramic layer,and the composition of the third dielectric ceramic layer are preferablydifferent from one another.

It should be noted that, in a case in which the third dielectric ceramiclayer includes a plurality of dielectric ceramic layers, the pluralityof dielectric ceramic layers of the third dielectric ceramic layer maybe the same composition relative to each other, or may be differentcompositions from each other. In a case in which any one composition ofthe plurality of dielectric ceramic layers of the third dielectricceramic layer is different from that of the first dielectric ceramiclayer, it can be recognized that the composition of the third dielectricceramic layer is different from the composition of the first dielectricceramic layer. Furthermore, in a case in which any one composition ofthe plurality of dielectric ceramic layers of the third dielectricceramic layer is different from that of the second dielectric ceramiclayer, it can be recognized that the composition of the third dielectricceramic layer is different from the composition of the second dielectricceramic layer.

Among the first dielectric ceramic layer, the second dielectric ceramiclayer, and the third dielectric ceramic layer, it is preferable for thedielectric ceramic layers having different compositions to have commonmain components and different types of additives. Examples of the maincomponent include BaTiO₃, CaTiO₃, and SrTiO₃. The additives preferablyinclude elements such as Si, Mg, Mn, Sn, Cu, rare earth, Ni and Al, forexample. The first dielectric ceramic layer, the second dielectricceramic layer, and the third dielectric ceramic layer may include two ormore of the above elements.

It should be noted that “the same composition” means that the types ofelements included in the dielectric ceramics included in each dielectricceramic layer are the same, and the content (molar ratio) of all otherelements based on Ti is within ±about 0.5%. It should be noted that thedifference in diameter of the ceramic grains included in each dielectricceramic layer, and the difference in porosity shall not be included inthe difference in the composition of the dielectric ceramic layer.

The composition of each of the dielectric ceramic layers can bedetermined by performing an elemental analysis by wavelength dispersiveX-ray analysis (WDX) or transmission electron microscopy-energydispersive X-ray analysis (TEM-EDX) on an exposed cut surface of adielectric ceramic layer made by cutting a multilayer ceramic capacitor.At this time, the composition of each dielectric ceramic layer ismeasured at five locations to determine the average value. Thecomposition of the second dielectric ceramic layer is measured at fivelocations from the second dielectric ceramic layer exposed on the firstend surface of the multilayer body, and at five locations from thesecond dielectric ceramic layer exposed on the second end surface of themultilayer body to determine the average value. In a case in which thethird dielectric ceramic layer has a multi-layered structure, thecomposition thereof is the sum of the compositions obtained bymultiplying the compositions obtained by measuring the composition ofeach of the layers at five locations with the ratio of the thickness ofeach of the layers occupied in the third dielectric ceramic layer. Itshould be noted that, when segregation of elements is observed in thevicinity of the interface with the other dielectric ceramic layer or theinternal electrode layer, the portion where segregation of elements isobserved shall not be the measurement target of WDX.

The element to be added to the first dielectric ceramic layer ispreferably Mg, for example. The content of Mg in the first dielectricceramic layer is preferably about 0.05 mol % or more and about 3.0 mol %or less, for example, with respect to 100 moles of Ti. The content of Mgin the first dielectric ceramic layer is more preferably less than thecontent of Mg in the second dielectric ceramic layer and the thirddielectric ceramic layer. When the content of Mg in the first dielectricceramic layer is small, since the relative dielectric constant of thefirst dielectric ceramic layer is increased, it is possible to improvethe capacitance of the multilayer ceramic capacitor. It should be notedthat the content of Mg in the first dielectric ceramic layer maypreferably be as low as possible.

The element to be added to the second dielectric ceramic layer ispreferably Sn, for example. The content of Sn in the second dielectricceramic layer is preferably about 0.05 mol % or more, and about 3.0 mol% or less, for example, with respect to 100 moles of Ti. The content ofSn in the second dielectric ceramic layer is preferably greater than thecontent of Sn in the first dielectric ceramic layer and the thirddielectric ceramic layer.

The element to be added to the third dielectric ceramic layer ispreferably Si, for example. The content of Si in the third dielectricceramic layer is preferably about 0.05 mol % or more, and about 5.0 mol% or less, for example, with respect to 100 moles of Ti. The content ofSi in the third dielectric ceramic layer is preferably greater than thecontent of Si in the first dielectric ceramic layer and the seconddielectric ceramic layer. When the content of Si in the third dielectricceramic layer is large, since the sinterability of the dielectricceramic layer is increased, it is possible to reduce or prevent theinternal electrode layer from being deteriorated due to the intrusion ofwater or the like from the first side surface and the second sidesurface of the multilayer body.

The element to be added to the third dielectric ceramic layer ispreferably Mg, for example. The content of Mg in the third dielectricceramic layer is preferably about 0.05 mol % or more and about 5.0 mol %or less, for example with respect to 100 moles of Ti. The content of Mgin the third dielectric ceramic layer is preferably greater than thecontent of Mg in the first dielectric ceramic layer and the seconddielectric ceramic layer. When the content of Mg in the third dielectricceramic layer is large, it is possible to reduce or prevent the graingrowth of the ceramic grains included in the third dielectric ceramiclayer, and it is possible to reduce or prevent a short circuit betweenthe internal electrode layers.

The element to be added to the third dielectric ceramic layer ispreferably Mn, for example. The content of Mn in the third dielectricceramic layer is preferably about 0.01 mol % or more, and about 3.0 mol% or less, for example, with respect to 100 moles of Ti. The content ofMn in the third dielectric ceramic layer is preferably greater than thecontent of Mn in the first dielectric ceramic layer and the seconddielectric ceramic layer. When the content of Mn in the third dielectricceramic layer is large, it is possible to reduce or prevent the graingrowth of the ceramic grains included in the third dielectric ceramiclayer, and it is possible to reduce or prevent a short circuit betweenthe internal electrode layers.

In the first dielectric ceramic layer, the second dielectric ceramiclayer, and the third dielectric ceramic layer, elements other than themain component included in each dielectric ceramic layer are preferablydiffused into the other dielectric ceramic layers. Furthermore, aportion of the elements included as an additive in the first dielectricceramic layer, the second dielectric ceramic layer, and the thirddielectric ceramic layer is preferably diffused into the adjacent otherdielectric ceramic layers and the internal electrode layers.

FIG. 5 is a cross-sectional view taken along line B-B of the multilayerceramic capacitor shown in FIG. 1. It should be noted that FIG. 5 is anLW cross-section of the multilayer ceramic capacitor 1. As shown in FIG.5, the second internal electrode layer 22 is exposed on the second endsurface 16 of the multilayer body 10, and the second dielectric ceramiclayer 20 b is exposed on the first end surface 15 of the multilayer body10. Furthermore, the third dielectric ceramic layer 41 and the thirddielectric ceramic layer 42 are respectively disposed on the first sidesurface 13 side and the second side surface 14 side of the multilayerbody 10.

As shown in FIG. 5, there is an interface 2220 b between the secondinternal electrode layer 22 and the second dielectric ceramic layer 20b. Furthermore, there are interfaces 2241 and 2242 between the secondinternal electrode layer 22 and the third dielectric ceramic layers 41and 42. Furthermore, there are interfaces 20 b 41 and 20 b 42 betweenthe second dielectric ceramic layer 20 b and the third dielectricceramic layers 41 and 42.

In addition, although not shown in FIG. 5, the first dielectric ceramiclayer 20 a is disposed on both sides in the thickness direction of thesecond internal electrode layer 22 and the second dielectric ceramiclayer 20 b. Therefore, it can be recognized that the first dielectricceramic layer 20 a includes an interface in direct contact with thesecond dielectric ceramic layer 20 b, the third dielectric ceramiclayers 41 and 42, and the internal electrode layers 21 and 22.

Furthermore, similarly to the second internal electrode layer 22 shownin FIG. 5, the first internal electrode layer 21 also includes aninterface in direct contact with the first dielectric ceramic layer 20a, the second dielectric ceramic layer 20 b, and the third dielectricceramic layers 41 and 42.

In the first dielectric ceramic layer 20 a, elements derived from thesecond dielectric ceramic layer 20 b may be segregated in the vicinityof the interface with the second dielectric ceramic layer 20 b.Furthermore, in the first dielectric ceramic layer 20 a, elementsoriginating from the third dielectric ceramic layer 41 or 42 may besegregated in the vicinity of the interface with the third dielectricceramic layer 41 or 42.

In the second dielectric ceramic layer 20 b, elements originating fromthe first dielectric ceramic layer 20 a may be segregated in thevicinity of the interface with the first dielectric ceramic layers 20 a.Furthermore, in the second dielectric ceramic layer 20 b, elementsoriginating from the third dielectric ceramic layer 41 or 42 may besegregated in the vicinity of the interfaces 20 b 41 or 20 b 42 with thethird dielectric ceramic layer 41 or 42.

In the third dielectric ceramic layers 41 and 42, elements originatingfrom the first dielectric ceramic layer 20 a may be segregated in thevicinity of the interface with the first dielectric ceramic layer 20 a.Furthermore, in the third dielectric ceramic layers 41 and 42, elementsoriginating from the second dielectric ceramic layer 20 b may besegregated in the vicinity of the interfaces 20 b 41 and 20 b 42 withthe second dielectric ceramic layer 20 b.

In the first internal electrode layer 21 and the second internalelectrode layer 22, elements originating from the first dielectricceramic layer 20 a may be segregated in the vicinity of the interfacewith the first dielectric ceramic layer 20 a. In addition, in the firstinternal electrode layer 21 and the second internal electrode layer 22,elements originating from the second dielectric ceramic layer 20 b maybe segregated in the vicinity of the interface 2220 b with the seconddielectric ceramic layer 20 b. Furthermore, in the first internalelectrode layer 21 and the second internal electrode layer 22, elementsoriginating from the third dielectric ceramic layers 41 and 42 may besegregated in the vicinity of the interfaces 2241 and 2242 with thethird dielectric ceramic layers 41 and 42. In addition, both the elementoriginating from the second dielectric ceramic layer 20 b and theelement originating from the third dielectric ceramic layer 41 or 42 maybe segregated in the vicinity of the portion where the interface 2220 bbetween the second internal electrode layer 22 and the second dielectricceramic layer 20 b, and the interface 2241 or 2242 between the secondinternal electrode layer 22, and the third dielectric ceramic layer 41or 42 are in contact with each other (the corner of the second internalelectrode layer 22 on the first end surface 15 side).

The porosity of the first dielectric ceramic layer, the seconddielectric ceramic layer, and the third dielectric ceramic layer may bethe same as, or may be different from one another. A multilayer ceramiccapacitor is cut, and the cut surface, which exposes each dielectricceramic layer, is observed by a scanning electron microscope (SEM) at20,000 times magnification. An area having a visual field size of about6.3 μm×about 4.4 μm is photographed at five locations so that the areasdo not overlap each other, and the ratio of the area occupied by thevoids to the entire visual field is calculated as the porosity by imageanalysis from each of the obtained SEM images, and an average value inthe five visual fields is obtained. However, in a case in which thethird dielectric ceramic layer includes a plurality of layers, theporosity of the third dielectric ceramic layer is calculated as the sumof the product of porosity of each layer and the value obtained bydividing the thickness of the layer by the thickness of the thirddielectric ceramic layer after obtaining the porosity of each layerindividually.

The first dielectric ceramic layer, the second dielectric ceramic layer,and the third dielectric ceramic layer preferably include ceramicgrains. When the dielectric ceramic layer includes ceramic grains,interfacial resistance occurs at the interface between the ceramicgrains, a result of which the insulation resistance between the internalelectrode layers increases, making it possible to reduce or prevent theoccurrence of a short circuit.

A rare earth element is preferably present at the interface of theceramic grains. The presence of a rare earth element at the interface ofthe ceramic grains can be confirmed by elemental analyses with TEM-EDX.Examples of the rare earth elements include La, Ce, Pr, Nd, Sm, Eu, Gd,Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. The presence of a rare earth elementat the interface of the ceramic grains allows for further increase ofthe interfacial resistance of the dielectric ceramic layer, as a resultof which it is possible to further improve the reliability of themultilayer ceramic capacitor. It should be noted that Mg, Mn, Si or thelike may also be present.

The rare earth element is preferably present in an amount of about 0.2mol % or more and about 5 mol % or less, for example, with respect to100 moles of Ti. Herein, 100 moles of Ti defines the amount of rareearth element with respect to 100 moles of Ti on the assumption that thedielectric ceramic material of the dielectric ceramic layers has acompound having a perovskite structure (structure represented by ABO₃,B=Ti) as a main component. The amount of rare earth element can beconfirmed by TEM-EDX.

In the multilayer ceramic capacitor, the thickness of each of the firstinternal electrode layer and the second internal electrode layer ispreferably about 0.4 μm or less, for example. Furthermore, the thicknessof each of the first internal electrode layer and the second internalelectrode layer is preferably about 0.38 μm or less, for example.Furthermore, the thickness of each of the first internal electrode layerand the second internal electrode layer is preferably about 0.25 μm ormore, for example.

The thickness of the first dielectric ceramic layer is preferably about0.55 μm or less, for example. Furthermore, the thickness of the firstdielectric ceramic layer is preferably about 0.4 μm or more, forexample.

The thickness of the second dielectric ceramic layer is preferably thesame or substantially the same as the thickness of the internalelectrode layer.

The thickness of each of the third dielectric ceramic layers 41 and 42is preferably about 5 μm or more and about 40 μm or less, and morepreferably about 5 μm or more and about 20 μm or less, for example. Thethicknesses of the third dielectric ceramic layers 41 and 42 arepreferably the same or substantially the same. However, the outer layer41 b is preferably thicker than the inner layer 41 a, while the innerlayer 41 a and the outer layer 41 b satisfy the above range. Similarly,the outer layer 42 b is preferably thicker than the inner layer 42 a,while the inner layer 42 a and the outer layer 42 b satisfy the aboverange.

From the viewpoint of maintaining the shape and performance of themultilayer ceramic capacitor 1, the inner layer 41 a is preferablythinner than the outer layer 41 b. Similarly, the inner layer 42 a ispreferably thinner than the outer layer 42 b.

The thickness of each of the inner layers 41 a and 42 a is preferablyabout 0.1 μm or more and about 20 μm or less, for example. The innerlayers 41 a and 42 a preferably have the same or substantially the samethickness.

The thickness of each of the outer layers 41 b and 42 b is preferablyabout 5 μm or more and about 20 μm or less, for example. The outerlayers 41 b and 42 b have preferably the same or substantially the samethickness.

The thickness of each ceramic layer of the side margin portion indicatesan average value when the thickness of the third dielectric ceramiclayer along the stacking (T) direction is measured at a plurality oflocations.

Method for Manufacturing a Multilayer Ceramic Capacitor

A method for manufacturing a multilayer ceramic capacitor according to apreferred embodiment of the present invention includes preparing a greenchip, the green chip including a multilayer structure including aplurality of first dielectric ceramic layers, a plurality of seconddielectric ceramic layers, and a plurality of pairs of first internalelectrode layers and second internal electrode layers in an unfiredstate, the first internal electrode layers and the second internalelectrode layers being exposed on a first side surface and a second sidesurface on opposite sides in a width direction orthogonal orsubstantially orthogonal to a stacking direction; forming an unfiredthird dielectric ceramic layer on the first side surface and the secondside surface of the green chip, and thus fabricating an unfiredmultilayer body; and firing the unfired multilayer body, in which thepreparing of the green chip further includes stacking a ceramic greensheet obtained by forming an unfired first internal electrode layer oran unfired second internal electrode layer on a surface of the unfiredfirst dielectric ceramic layer and forming an unfired second dielectricceramic layer in a region where the first internal electrode layer andthe second internal electrode layer are not provided, in which thefabricating the unfired multilayer body further includes forming anunfired side margin portion by forming an unfired inner layer on thefirst side surface and the second side surface and forming an unfiredouter layer on an outermost side, and in which a composition of at leastone dielectric ceramic layer among the first dielectric ceramic layer,the second dielectric ceramic layer, and the third dielectric ceramiclayer is different from that of the other dielectric ceramic layers.

A non-limiting example of a method for manufacturing the multilayerceramic capacitor 1 shown in FIG. 1 will be described below.

First, a ceramic green sheet is prepared which is to be provided withthe first dielectric ceramic layer 20 a, the second dielectric ceramiclayer 20 b, and the third dielectric ceramic layers 41 and 42. Theceramic green sheet includes a binder, a solvent, and the like, inaddition to a ceramic raw material including the dielectric ceramicmaterial described above. Furthermore, an additive including a rareearth element may be added to the ceramic raw material. By changing theelement included in the additive, the compositions of the firstdielectric ceramic layer, the second dielectric ceramic layer, and thethird dielectric ceramic layer can be changed. The ceramic raw materialsas a main component are preferably the same or substantially the same.The ceramic green sheet is molded using, for example, a die coater, agravure coater, a micro gravure coater, or the like, on a carrier film.

FIGS. 6, 7, and 8 are plan views schematically showing an example of aceramic green sheet. FIGS. 6, 7, and 8 respectively show a first ceramicgreen sheet 101 for forming the inner layer portion 30, a second ceramicgreen sheet 102 for forming the inner layer portion 30, and a thirdceramic green sheet 103 for forming the outer layer portion 31 or 32.

In FIGS. 6, 7, and 8, the first ceramic green sheet 101, the secondceramic green sheet 102, and the third ceramic green sheet 103 are notseparated into each multilayer ceramic capacitor 1. In FIGS. 6, 7, and8, the cutting lines X and Y at the time of separating into eachmultilayer ceramic capacitor 1 are shown. The cutting line X is parallelor substantially parallel to the length (L) direction, and the cuttingline Y is parallel or substantially parallel to the width (W) direction.

As shown in FIG. 6, in the first ceramic green sheet 101, an unfiredfirst internal electrode layer 121 corresponding to the first internalelectrode layer 21 is formed on an unfired first dielectric ceramiclayer 120 a corresponding to the first dielectric ceramic layer 20 a.Furthermore, an unfired second dielectric ceramic layer 120 bcorresponding to the second dielectric ceramic layer 20 b is formed in aregion where the unfired first internal electrode layer 121 is notformed. The unfired first dielectric ceramic layer 120 a and the unfiredsecond dielectric ceramic layer 120 b also refer to an unfireddielectric ceramic layer 120 corresponding to the dielectric ceramiclayer 20.

As shown in FIG. 7, in the second ceramic green sheet 102, an unfiredsecond internal electrode layer 122 corresponding to the second internalelectrode layer 22 is formed on the unfired first dielectric ceramiclayer 120 a corresponding to the first dielectric ceramic layer 20 a.Furthermore, the unfired second dielectric ceramic layer 120 bcorresponding to the second dielectric ceramic layer 20 b is formed in aregion where the unfired second internal electrode layer 122 is notformed. The unfired first dielectric ceramic layer 120 a and the unfiredsecond dielectric ceramic layer 120 b also refer to the unfireddielectric ceramic layer 120 corresponding to the dielectric ceramiclayer 20.

The method for fabricating the first ceramic green sheet 101 shown inFIG. 6 and the second ceramic green sheet shown in FIG. 7 is notparticularly limited. However, examples thereof include a method forapplying a dielectric paste as the mixture of a dielectric ceramic and asolvent, which becomes the second dielectric ceramic layer 20 b byfiring, and a conductive paste, which becomes the internal electrodelayer 21 or 22 by firing, respectively to predetermined regions of thesurface of the unfired first dielectric ceramic layer 120 a. The orderin which the dielectric paste and the conductive paste are applied isnot particularly limited, and the conductive paste may be applied afterthe dielectric paste is applied first, or the dielectric paste may beapplied after the conductive paste is applied first. In addition, thedielectric paste and the conductive paste may be applied so that aportion of the surface of the paste applied previously is covered with aportion of the paste applied later.

As shown in FIG. 8, the third ceramic green sheet 103 corresponding tothe outer layer portion 31 or 32 includes the unfired first dielectricceramic layer 120 a corresponding to the first dielectric ceramic layer,and neither the unfired internal electrode layer 121 or 122 nor theunfired second dielectric ceramic layer 120 b is formed.

The first internal electrode layer 121 and the second internal electrodelayer 122 can be formed using any conductive paste. For example, ascreen-printing method, a gravure printing method, or the like can beused for forming the first internal electrode layer 121 and the secondinternal electrode layer 122 using the conductive paste.

The first internal electrode layer 121 and the second internal electrodelayer 122 are disposed over two regions which are partitioned by thecutting line Y and are adjacent to each other in the length (L)direction, and extend in a strip shape in the width (W) direction. Theregions partitioned by the cutting line Y of the first internalelectrode layer 121 and the second internal electrode layer 122 areshifted from each other in the length (L) direction by one row. That is,the cutting line Y passing through the center of the first internalelectrode layer 121 passes through a region between the second internalelectrode layers 122 (i.e., the center of the second dielectric ceramiclayer 120 b), and the cutting line Y passing through the center of thesecond internal electrode layer 122 passes through the region betweenthe first internal electrode layers 121 (i.e., the center of the seconddielectric ceramic layer 120 b).

Thereafter, the first ceramic green sheet 101, the second ceramic greensheet 102, and the third ceramic green sheet 103 are stacked, thusfabricating a mother block.

FIG. 9 is an exploded perspective view schematically showing an exampleof the mother block. In FIG. 9, for convenience of explanation, thefirst ceramic green sheet 101, the second ceramic green sheet 102, andthe third ceramic green sheet 103 are shown in an exploded manner.However, in an actual mother block 104, the first ceramic green sheet101, the second ceramic green sheet 102, and the third ceramic greensheet 103 are integrally crimped by hydrostatic pressing, or the like,for example.

In the mother block 104 shown in FIG. 9, the first ceramic green sheet101 and the second ceramic green sheet 102 corresponding to the innerlayer portion 30 are alternately stacked in the stacking (T) direction.Furthermore, the third ceramic green sheets 103 corresponding to theouter layer portions 31 and 32 are stacked on the upper and lowersurfaces in the stacking (T) direction of the first ceramic green sheets101 and the second ceramic green sheets 102 which are alternatelystacked. It should be noted that, although the third ceramic green sheet103 is configured such that three pieces of the first dielectric ceramiclayer 120 a are stacked in FIG. 9, the number of first dielectricceramic layers 120 a to be stacked can be changed as appropriate.

By cutting the resulting mother block 104 along the cutting lines X andY (refer to FIGS. 6, 7, and 8), a plurality of green chips arefabricated. For this cutting, a method such as dicing, push cutting, orlaser cutting is applied, for example.

FIG. 10 is a perspective view schematically showing an example of agreen chip. The green chip 110 shown in FIG. 10 has a multilayerstructure including the plurality of first dielectric ceramic layers 120a and the plurality of second dielectric ceramic layers 120 b, and theplurality of pairs of first internal electrode layers 121 and secondinternal electrode layers 122 in an unfired state. A first side surface113 and a second side surface 114 of the green chip 110 are planesprovided by cutting along the cutting line X, and a first end surface115 and a second end surface 116 are planes provided by cutting alongthe cutting line Y. The first internal electrode layer 121 and thesecond internal electrode layer 122 are exposed on the first sidesurface 113 and the second side surface 114. Furthermore, only the firstinternal electrode layers 121 and the second dielectric ceramic layer120 b are exposed on the first end surface 115, and only the secondinternal electrode layer 122 and the second dielectric ceramic layer 120b are exposed on the second end surface 116. The first dielectricceramic layer 120 a is exposed on the first side surface 113, the secondside surface 114, the first end surface 115, and the second end surface116. However, the locations of the second dielectric ceramic layers thatare exposed in a region to be disposed differ. In other words, thesecond dielectric ceramic layers 120 b disposed at a side of the firstend surface 115 is not exposed on the second end surface 116, and thesecond dielectric ceramic layer 120 b disposed at a side of the secondend surface 116 is not exposed on the first end surface 115.

An unfired third dielectric ceramic layer is formed on the first sidesurface 113 and the second side surface 114 of the resulting green chip110, as a result of which an unfired multilayer body is fabricated. Theunfired third dielectric ceramic layer is formed, for example, bypasting a ceramic green sheet made of a dielectric ceramic on the firstside surface and the second side surface of the green chip.

For example, in a case in which the third dielectric ceramic layerincludes two layers of the inner layer and the outer layer, first, inorder to fabricate a ceramic green sheet for the inner layer, a ceramicslurry is produced which includes a binder, a solvent, and the like, inaddition to the ceramic raw material including a dielectric ceramicmaterial mainly including BaTiO₃ or the like. Si as a sintering aid maybe added to the ceramic slurry for the inner layer. The inner layer hasa function of adhering to the green chip 110. In addition, a liquidphase metal may be added to the ceramic slurry for the inner layer, andmore rare earth elements, Mg, and Mn may be added to the ceramic slurryfor the inner layer than to the ceramic green sheet for forming theinner layer portion. Thus, it is possible to reduce or prevent the graingrowth of the ceramic grains included in the dielectric ceramic layersandwiched by the width direction ends of the internal electrode layers.

Next, in order to fabricate a ceramic green sheet for the outer layer, aceramic slurry including a binder, a solvent, and the like in additionto a ceramic raw material including a dielectric ceramic materialincluding BaTiO₃ or the like as a main component is produced. Inaddition, Si as a sintering aid may be added to the ceramic slurry forthe outer layer. Furthermore, Si included in the ceramic green sheet forthe inner layer is preferably larger than Si included in the ceramicgreen sheet for the outer layer. The degree of the content is determinedbased on the size of the area of a region where Si is detected, byimaging the cross-section by WDX.

The ceramic slurry for the outer layer is applied to the surface of aresin film and dried, such that the ceramic green sheet for the outerlayer is formed. The ceramic slurry for the inner layer is applied tothe surface of the ceramic green sheet for the outer layer on the resinfilm and dried, such that the ceramic green sheet for the inner layer isformed. As described above, a ceramic green sheet having a two-layerstructure is obtained.

It should be noted that the ceramic green sheet having the two-layerstructure can also be obtained, for example, by forming the ceramicgreen sheet for the outer layer and the ceramic green sheet for theinner layer in advance, and then bonding them to each other.Furthermore, the ceramic green sheet is not limited to the two-layerstructure, and may have a structure with three or more layers.

Thereafter, the ceramic green sheet is peeled from the resin film.

Subsequently, the ceramic green sheet for the inner layer of the ceramicgreen sheet and the first side surface 113 of the green chip 110 aremade to face each other, and pressed and punched, thus forming theunfired side margin portion 41. Furthermore, the ceramic green sheetsfor the inner layer of the ceramic green sheet and the second sidesurface 114 of the green chip 110 are also made to face each other, andpressed and punched, thus forming the unfired side margin portion 42. Atthis time, an organic solvent defining and functioning as an adhesive ispreferably applied to the side surface of the green chip in advance. Asdescribed above, an unfired multilayer body is obtained.

It is preferable to perform barrel polishing or the like, for example,on the unfired multilayer body obtained by the above method. Bypolishing the unfired multilayer body, the corners and ridges of a firedmultilayer body 10 are rounded.

Thereafter, in the unfired multilayer body, a conductive paste for anexternal electrode including Ni and a ceramic material is applied oneach end surface of the first end surface 115 and the second end surface116 of the green chip 110.

The conductive paste for the external electrode preferably includes, asa ceramic material, the same or substantially the same dielectricceramic material as the first dielectric ceramic layer, the seconddielectric ceramic layer, or the outer layer. The content of the ceramicmaterial in the conductive paste for the external electrodes ispreferably about 15% by weight or more, for example. Furthermore, thecontent of the ceramic material in the conductive paste for the externalelectrode is preferably about 25% by weight or less, for example.

Next, the unfired multilayer body to which the conductive paste for theexternal electrode is subjected to, for example, a degreasing treatmentin a nitrogen atmosphere under a predetermined condition, and then theresulting multilayer body is fired at a predetermined temperature in anitrogen-hydrogen-water vapor mixed atmosphere. Thus, the unfiredmultilayer body and the conductive paste for the external electrode arefired simultaneously, and the multilayer body 10, the Ni layer connectedto the first internal electrode layer 21, and the Ni layer connected tothe second internal electrode layer 22 are formed at the same time by acofiring method. Thereafter, the first plated layer including Ni platingand the second plated layer including Sn plating are stacked in thisorder on the surface of each of the Ni layer. Thus, the first externalelectrode 51 and the second external electrode 52 are formed.

It should be noted that on the multilayer body 10, the first externalelectrode 51 and the second external electrode 52 may be formed atseparate timings by a post-firing method. Specifically, first, amultilayer body 10 is formed by performing a degreasing treatment on anunfired laminate under a predetermined condition in a nitrogenatmosphere, for example, and then firing the multilayer body at apredetermined temperature in a nitrogen-hydrogen-water vapor mixedatmosphere. Then, on each end surface of the first end surface 15 andthe second end surface 16 of the multilayer body 10, a conductive pasteincluding Cu powder is applied and baked. Thus, a foundation electrodelayer connected to the first internal electrode layer 21 and afoundation electrode layer connected to the second internal electrodelayer 22 are formed. Then, on the surface of each of the underlyingelectrode layer, conductive particles (e.g., Cu, Ag, Ni, metal particlessuch as) and a conductive resin layer including a resin, a first platedlayer including Ni plating, and a second plated layer including Snplating are laminated in this order. Thus, the first external electrode51 and the second external electrode 52 are formed.

Thus, the multilayer ceramic capacitor 1 is manufactured.

In the preferred embodiment described above, the unfired thirddielectric ceramic layer preferably is formed on both sides of the greenchip after obtaining the plurality of green chips by cutting the motherblock 104 along the cutting lines X and Y, for example. However, thefollowing modifications are also possible.

That is, it may be configured such that a plurality of rod-shaped greenblock bodies are obtained which are provided by cutting the mother blockalong only the cutting line X and in which the first internal electrodelayer and the second internal electrode layer are exposed on the sidesurface provided by cutting along the cutting line X, and thereafter,the unfired third dielectric ceramic layer is formed on both sides ofthe green block bodies to obtain a plurality of unfired multilayerbodies by cutting along the cutting line Y, followed by the unfiredmultilayer bodies being fired. By performing the same steps as in theabove-described preferred embodiment after firing, a multilayer ceramiccapacitor can be manufactured.

Preferred embodiments of the present invention further include thefollowing configurations of (1) to (7).

(1) Alloy Portion between the Dielectric Ceramic Layer and the InternalElectrode Layer and the External Electrode

In a multilayer ceramic capacitor 1 according to a preferred embodimentof the present invention, as shown in FIG. 11, a second alloy portion320 is provided between the second dielectric ceramic layer 20 b and thefirst internal electrode layer 21, and between the second dielectricceramic layer 20 b and the second internal electrode layer 22,respectively. Furthermore, in the multilayer ceramic capacitor 1, afirst alloy portion 310 is provided between the first dielectric ceramiclayer 20 a and the first internal electrode layer 21, and between thefirst dielectric ceramic layer 20 a and the second internal electrodelayer 22, respectively.

As shown in FIG. 12, metal elements 321 a are segregated at theinterface 2220 b with the second dielectric ceramic layer 20 b in thesecond internal electrode layer 22. The second alloy portion 320includes a segregation layer 321 which is a layer segregation by themetal elements 321 a. Similarly to this, the metal elements 321 a aresegregated to provide the segregation layer 321 also at the interface2220 b with the second dielectric ceramic layer 20 b in the firstinternal electrode layer 21, and the second alloy portion 320 by thesegregation layer 321 is provided. The second alloy portion 320 isprovided on the surfaces of the first internal electrode layer 21 andthe second internal electrode layer 22 closer to the second dielectricceramic layer 20 b, respectively. The second alloy portion 320 isprovided between the first internal electrode layer 21 and the seconddielectric ceramic layer 20 b, and between the second internal electrodelayer 22 and the second dielectric ceramic layer 20 b.

Furthermore, as shown in FIG. 12, metal elements 311 a are segregated atan interface 2220 a with the first dielectric ceramic layer 20 a in thesecond internal electrode layer 22. The first alloy portion 310 includesa segregation layer 311 which is a layer segregation by the metalelement 311 a. Similarly to this, the metal elements 311 a aresegregated to provide the segregation layer 311 at the interface 2220 awith the first dielectric ceramic layer 20 a in the first internalelectrode layer 21, and the first alloy portion 310 by the segregationlayer 311 is provided. The first alloy portion 310 is provided on thesurfaces of the first internal electrode layer 21 and the secondinternal electrode layer 22 closer to the first dielectric ceramic layer20 a, respectively. The first alloy portion 310 is provided between thefirst internal electrode layer 21 and the first dielectric ceramic layer20 a, and between the second internal electrode layer 22 and the firstdielectric ceramic layer 20 a.

There are a plurality of types of segregated metal elements 321 a in thesecond alloy portion 320. The plurality of types of metal elements 321 ain the segregation layer 321 includes a metal element provided in agreatest amount among the metal elements of the first internal electrodelayer 21 and the second internal electrode layer 22, and an elementderived from the second dielectric ceramic layer 20 b. Furthermore, thesame applies to the segregated metal element 311 a of the first alloyportion 310. That is, the metal element 311 a includes a metal elementprovided in a greatest amount among the metal elements of the firstinternal electrode layer 21 and the second internal electrode layer 22,and an element derived from the first dielectric ceramic layer 20 a.

Examples of the metal element provided in a greatest amount among themetal elements of the first internal electrode layer 21 and the secondinternal electrode layer 22 include one of Ni, Cu, Ag, Pd, Au, and Pt.On the other hand, examples of the element derived from the seconddielectric ceramic layer 20 b and the first dielectric ceramic layer 20a include a metal element as an additive. More specifically, examplesthereof include any one or more metal elements among the metal group ofSn, In, Ga, Zn, Bi, Pb, Cu, Ag, Pd, Pt, Ph, Ir, Ru, Os, Fe, V, Y, andGe, among which, Sn, Ga, and Ge is particularly preferred. Hereinafter,this metal group may be referred to as a metal group M.

The segregation of the metal element 321 a occurs when the metal elementincluded in the second dielectric ceramic layer 20 b migrates to thefirst internal electrode layer 21 and the second internal electrodelayer 22 during firing of the second dielectric ceramic layer 20 b.Furthermore, the segregation of the metal element 311 a occurs when themetal element included in the first dielectric ceramic layer 20 amigrates to the first internal electrode layer 21 and the secondinternal electrode layer 22 during firing of the first dielectricceramic layer 20 a.

In a case in which the first dielectric ceramic layer 20 a includesBaTiO₃ as a main component, the second alloy portion 320 has a highercontent of metal elements included in the second dielectric ceramiclayer 20 b, i.e. any one or more of the above metal group M in terms ofmolar ratio relative to 100 moles of Ti, than the first alloy portion310.

FIG. 13 shows a plane of the multilayer body 10 including a centralportion in the width (W) direction, and the length (L) direction and thestacking (T) direction. In the multilayer ceramic capacitor 1, in theplane shown in FIG. 13, the first internal electrode layer 21 includes aplurality of first interspersed internal electrodes 210 intersperseddiscontinuously in the length (L) direction at the end in the length (L)direction that is not connected to the second external electrode 52.Furthermore, the second internal electrode layer 22 includes a pluralityof second interspersed internal electrodes 220 intersperseddiscontinuously in the length (L) direction at the end in the length (L)direction that is not connected to the first external electrode 51. Eachof the first interspersed internal electrodes 210 and the secondinterspersed internal electrodes 220 is provided within the seconddielectric ceramic layer 20 b. The plurality of first interspersedinternal electrodes 210 may be connected to the first internal electrodelayer 21 while extending in the width (W) direction. Furthermore, theplurality of second interspersed internal electrodes 220 may also beconnected to the second internal electrode layer 22 while extending inthe width (W) direction.

A fourth alloy portion 340 is provided around each of the firstinterspersed internal electrode 210 and the second interspersed internalelectrode 220. The fourth alloy portion 340 is defined by a segregationlayer 341 which is a layer segregation by the metal element 341 a. Themetal element 341 a includes a metal element provided in a greatestamount among the metal elements of the first internal electrode layer 21and the second internal electrode layer 22, and one or more kinds ofmetal elements among the metal group M originating from the seconddielectric ceramic layer 20 b.

The segregation of the metal element 341 a occurs when the metal elementincluded in the second dielectric ceramic layer 20 b migrates to thefirst interspersed internal electrode 210 and the second interspersedinternal electrode 220 during firing of the second dielectric ceramiclayer 20 b. It should be noted that the segregation of the metal element341 a occurs around one or a plurality of the first interspersedinternal electrodes 210 and one or a plurality of the secondinterspersed internal electrodes 220. Alternatively, the segregation ofthe metal element 341 a may occur around the entire or substantially theentire periphery of the first interspersed internal electrode 210 andaround the entire or substantially the entire periphery of the secondinterspersed internal electrode 220.

As shown in FIG. 14, in the multilayer ceramic capacitor 1, a thirdalloy portion 330 is provided between the third dielectric ceramiclayers 41 and 42 and the first internal electrode layer 21, and betweenthe third dielectric ceramic layers 41 and 42 and the second internalelectrode layer 22, respectively.

As shown in FIG. 14, a metal element 331 a is segregated at an interface2220 c between the first internal electrode layer 21 and the thirddielectric ceramic layers 41 and 42. Furthermore, the metal element 331a is also segregated at the interface 2220 c with the third dielectricceramic layers 41 and 42 in the second internal electrode layer 22. Thethird alloy portion 330 provided by a layer segregation by the metalelement 331 a, i.e. a segregation layer 331. The third alloy portions330 are provided on the surfaces of the first internal electrode layer21 and the second internal electrode layer 22, closer to the thirddielectric ceramic layer 41 and 42, respectively. The third alloyportions 330 are provided between the first internal electrode layer 21and the third dielectric ceramic layers 41 and 42, and between thesecond internal electrode layer 22 and the third dielectric ceramiclayers 41 and 42, respectively.

The metal element 331 a includes a metal element provided in a greatestamount among the metal elements of the first internal electrode layer 21and the second internal electrode layer 22, and one or more kinds ofmetal elements among the metal group M originating from the thirddielectric ceramic layers 41 and 42. Examples of the elementsoriginating from the third dielectric ceramic layers 41 and 42 include ametal element as an additive. More specifically, examples thereofinclude any one or more of metal elements among the above metal group M.

The segregation of the metal element 331 a occurs when the metal elementincluded in the third dielectric ceramic layers 41 and 42 migrates tothe first internal electrode layer 21 and the second internal electrodelayer 22 during firing of the third dielectric ceramic layers 41 and 42.

In the multilayer ceramic capacitor 1, the first external electrode 51and the second external electrode 52 each include a Ni layer as afoundation electrode layer, and, when formed by a cofiring method, asshown in FIG. 15, a fifth alloy portion 350 is formed in the Ni layer.

FIG. 15 shows a state in which the fifth alloy portion 350 is providedat an interface 51 b with the second dielectric ceramic layer 20 b inthe first external electrode 51. The fifth alloy portion 350 is asegregation layer 351 which is a layer segregation by a metal element351 a. Similarly to this, the fifth alloy portion 350 due to thesegregation of the metal element 351 a is also provided at the interface51 b with the second dielectric ceramic layer 20 b in the secondexternal electrode 52. The segregation of the metal element 351 a occurswhen the metal element included in the second dielectric ceramic layer20 b migrates to the first external electrode 51 and the second externalelectrode 52 during firing of the second dielectric ceramic layer 20 b.

It should be noted that, in the multilayer body 10 of the multilayerceramic capacitor 1 of the present preferred embodiment, the ends of thefirst internal electrode layer 21, the second internal electrode layer22, and the second dielectric ceramic layer 20 b which are adjacent toeach other may overlap with each other. For example, as shown in FIG.16, the end of the second dielectric ceramic layer 20 b may besuperimposed on the end of the second internal electrode layer 22.Furthermore, as shown in FIG. 17, the end of the second dielectricceramic layer 20 b may overlap the end of the first internal electrodelayer 21. In such a configuration in which the ends overlap with eachother, the first internal electrode layer 21 and the second internalelectrode layer 22 may be superimposed on the second dielectric ceramiclayer 20 b.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the second alloy portion 320, which includes one metalelement provided in a greatest amount among the metal elements of theinternal electrode layer, and any one or more metal elements among themetal group M including Sn, In, Ga, Zn, Bi, Pb, Cu, Ag, Pd, Pt, Ph, Ir,Ru, Os, Fe, V, and Y, is provided between the second dielectric ceramiclayer 20 b and the first internal electrode layer 21, and between thesecond dielectric ceramic layer 20 b and the second internal electrodelayer 22, respectively.

The electric field is likely to be concentrated at the respective endsof the first internal electrode layer 21 and the second internalelectrode layer 22 in contact with the second dielectric ceramic layer20 b. For this reason, there is a possibility of lowering thereliability of a multilayer ceramic capacitor. However, according to themultilayer ceramic capacitor 1 of the present preferred embodiment, thesecond alloy portion 320 is provided between the second dielectricceramic layer 20 b, and the first internal electrode layer 21 and thesecond internal electrode layer 22, such that it is possible to reduceor prevent the electric field concentration, thus improving thereliability.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, in a case in which the first dielectric ceramic layer 20 aincludes Ba and Ti, the first alloy portion 310, which includes a metalelement provided in a greatest amount among the metal elements of theinternal electrode layer, and any one or more of metal elements amongthe above metal group M, is provided between the first dielectricceramic layer 20 a and the first internal electrode layer 21, andbetween the first dielectric ceramic layer 20 a and the second internalelectrode layer 22, respectively. The second alloy portion 320 has ahigher content of the above metal group M in terms of molar ratiorelative to 100 moles of Ti than the first alloy portion 310.

Thus, it is possible for the second alloy portion 320 to reduce orprevent the electric field concentration occurring at a portion in thevicinity of the interfaces with the second dielectric ceramic layer 20 bin the first internal electrode layer 21 and the second internalelectrode layer 22, thus improving the reliability. Furthermore, byincreasing the content of the metal group M of the second alloy portion320, which is provided at the ends of the first internal electrode layer21 and the second internal electrode layer 22 in contact with the seconddielectric ceramic layer 20 b where electric field concentration islikely to occur, in terms of molar ratio relative to 100 moles of Ti,more than the first alloy portion 310 provided closer to the firstdielectric ceramic layer 20 a, it is possible to effectively reduce theelectric field concentration on the second dielectric ceramic layer 20 bside, thus further improving the reliability.

By the amount of metal of the metal group M added to each of the firstdielectric ceramic layer 20 a and the second dielectric ceramic layer 20b being controlled, the thickness of the first alloy portion 310 and thesecond alloy portion 320, and the concentration of the metal group Mincluded therein can be controlled. For example, when the concentrationof the metal group M added to the second dielectric ceramic layer 20 bis higher than that of the first dielectric ceramic layer 20 a, as shownin FIG. 12, the thickness of the second alloy portion 320 increases, orthe concentration of the metal group M increases as it approaches thesecond dielectric ceramic layer 20 b, or in some cases, the thickness ofthe second alloy portion 320 increases, and the concentration of themetal group M increases as it approaches the second dielectric ceramiclayer 20 b.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, in the plane of the multilayer body 10 including the centralportion in the width (W) direction, the length (L) direction, and thestacking (T) direction, the first internal electrode layer 21 includesthe first interspersed internal electrodes 210 that are discontinuouslyinterspersed in the length (L) direction at the end in the length (L)direction that is not connected to the second external electrode 52, thesecond internal electrode layer 22 includes the second interspersedinternal electrodes 220 that are discontinuously interspersed in thelength (L) direction at the end in the length (L) direction that is notconnected to the first external electrode 51, and the fourth alloyportion 340, which includes a metal element provided in a greatestamount among the metal elements of the internal electrode layer, and anyone or more of metal elements among the metal group M, is providedaround each of the first interspersed internal electrodes 210 and thesecond interspersed internal electrodes 220.

When the first intersecting internal electrode 210 and the secondintersecting internal electrode 220 are respectively connected to thefirst internal electrode layer 21 and the second internal electrodelayer 22 while extending in the width (W) direction, if the electricfield is concentrated in the connecting portion, breakdown may occurwhich reduces reliability. However, according to the multilayer ceramiccapacitor 1 of the present preferred embodiment, it is possible for thefourth alloy portion 340 provided around each of the first interspersedinternal electrodes 210 and the second interspersed internal electrodes220 to reduce or prevent breakdown due to electric field concentration,such that it is possible to improve the reliability.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the third alloy portion 330, which includes a metal elementprovided in a greatest amount among the metal elements of the internalelectrode layer, and any one or more of metal elements among the abovemetal group M, is provided between the third dielectric ceramic layer 41and 42 and the first internal electrode layer 21, and between the thirddielectric ceramic layer 41 and 42 and the second internal electrodelayer 22, respectively.

Thus, the electric field concentration is reduced or prevented at theportion in the vicinity of the interfaces with the third dielectricceramic layers 41 and 42 in the first internal electrode layer 21 andthe second internal electrode layer 22 by the third alloy portion 330,thus making it possible to improve the reliability.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the first external electrode 51 and the second externalelectrode 52 include Ni, and the fifth alloy portion 350 in which anyone or more of metal elements among the metal group M is segregated inNi is provided between the second dielectric ceramic layer 20 b, and thefirst external electrode 51 and the second external electrode 52.

Thus, even when the interval between the first internal electrode layer21 and the second external electrode 52, and the interval between thesecond internal electrode layer 22 and the first external electrode 51,i.e. the distance of the second dielectric ceramic layer 20 b in thelength (L) direction is, for example, as narrow as less than about 15μm, since the fifth alloy portion 350 is present, which causes breakdowndue to electric field concentration to be less likely to occur betweenthe internal electrode layer and the external electrode, reliability isimproved.

Test Example 1

Next, Test Example 1 will be described which verifies the advantageouseffects of the first alloy portion 310, the second alloy portion 320,and the third alloy portion 330 in the multilayer ceramic capacitor 1 ofthe present preferred embodiment.

Regarding TEM Analysis

In the manufacturing method for the multilayer ceramic capacitor of thepresent preferred embodiment described above, the multilayer body 10obtained by firing the green chip 110 without cofiring the firstexternal electrode 51 and the second external electrode 52 is polishedfrom the first side surface 13 side and the second side surface 14 side,to obtain a polished body leaving the central portion in the width (W)direction as a test body, as shown in FIG. 18. The type and the amountof metal (metal concentration) of the metal elements included in thefirst alloy portion 310 were analyzed as follows. As shown in FIG. 18,in the central portion of the length (L) direction, an imaginary lineOL1 orthogonal or substantially orthogonal to the length (L) directionwas assumed. Furthermore, the region in which the first dielectricceramic layer 20 a in relation to the acquisition of the capacitance ofthe polished body, and the first internal electrode layer 21 and thesecond internal electrode layer 22 are stacked is equally divided intothree regions along the imaginary line OL1 in the stacking direction.The three regions include an upper region E1, a center region E2, and alower region E3. The upper region E1, the center region E2, and thelower region E3 are cut out from the polished body, and each of theupper region E1, the center region E2, and the lower region E3 isthinned by Ar ion milling or the like, for example, to obtain three thinfilm samples from each region.

The three thin film samples of the upper region E1, the center regionE2, and the lower region E3 of the test body obtained as described abovewere subjected to TEM observation and elemental mapping by EDX attachedto the TEM. As a result, since there was no significant differencebetween the upper region E1 and the lower region E3, and the centerregion E2, the result obtained from the center region E2 is regarded asthe microstructure including the dielectric ceramic layer and theinternal electrode layer. As a result, the type and the amount of metal(metal concentration) of the metal elements included in the first alloyportion 310 are known. In addition, the type and the amount of metal(metal concentration) of the metal elements included in the second alloyportion 320 can be analyzed by obtaining a thin film sample in the sameor substantially the same manner as described above in the region of oneend in the length (L) direction in which the second alloy portion 320exists. That is, in the polished body shown in FIG. 18, an imaginaryline OL2 orthogonal or substantially orthogonal to the length (L)direction is assumed at one end in the length (L) direction, to obtainthin film samples of three regions including an upper region E4, acenter region E5, and a lower region E6 which are provided by dividinginto three equal portions along the imaginary line OL2 in the stackingdirection. Furthermore, the three thin film samples of the upper regionE4, the center region E5, and the lower region E6 were subjected to TEMobservation and element mapping by EDX attached to TEM, to examine thetype and the amount of metal (metal concentration) included in thesecond alloy portion 320.

For the second alloy portion and the first alloy portion, theconcentration of Sn was examined by analysis with EDX mapping image by aTEM observation image. The TEM measurement points were measured atintervals of about 5 nm to about 10 nm. At the interface between theinternal electrode layer and the dielectric ceramic layer, the regionobtained three times or more of the observed values than the othermeasurement points is regarded as the alloy portion, and the averagevalue is regarded as the metal concentration of the alloy portion.

Eighteen multilayer ceramic capacitors were prepared for each of TestExamples 1-1 to 1-5 shown in Table 1. In Test Example 1-2, in themultilayer ceramic capacitor of the present preferred embodiment, thefirst internal electrode layer 21 and the second internal electrodelayer 22 were made of Ni, and the same amount of Sn as an additive wasadded to the first dielectric ceramic layer 20 a and the seconddielectric ceramic layer 20 b. In Test Examples 1-3 to 1-5, the amountof Sn added to the second dielectric ceramic layer 20 b was graduallylarger than that in Test Example 1-2. Furthermore, in Test Example 1-1,multilayer ceramic capacitors of the same conditions as those in TestExamples 1-2 to 1-5 were used, except that no Sn was added to the seconddielectric ceramic layer 20 b.

For the multilayer ceramic capacitors of Test Examples 1-1 to 1-5, thedetermination was made by measuring the resistance value (kΩ) in a statein which a voltage of about 6.3 V was applied in an environment with aroom temperature of about 150° C., to examine MTTF (mean failure time).MTTF was determined when the resistance value became about 10 kΩ orless, and if MTTF was about 15.3 hours (hr) or less, it was evaluated asfail, if MTTF was up to about 30 hours beyond about 15.3 hours (hr), itis evaluated as good, and if MTTF was beyond about 30 hours, it wasevaluated as excellent. The results are listed in Table 1. It should benoted that, when the coverage of the internal electrode layer is lessthan about 80%, since the capacitance is difficult to be measured, itwas evaluated as unmeasurable.

TABLE 1 Sn Sn CONCENTRATION CONCENTRATION OF FIRST OF SECOND ALLOYPORTION ALLOY PORTION (at %) (at %) MTTF (hr) EVALUATION TEST EXAMPLE 10 15.3 FAIL 1-1 TEST EXAMPLE 1 1 21 GOOD 1-2 TEST EXAMPLE 1 1.1 21 GOOD1-3 TEST EXAMPLE 1 1.3 23 GOOD 1-4 TEST EXAMPLE 1 1.4 35 EXCELLENT 1-5

According to Table 1, it is confirmed that, since the second alloyportion was provided, MTTF was beyond the prescribed time of about 15.3hours, and thus it was evaluated as good, and it is further found thatMTTF was better as the Sn concentration was higher. On the other hand,in Test Example 1-1 in which the second alloy portion including Sn wasnot provided, MTTF could not exceed the prescribed time. Thus, it wasconfirmed that the second alloy portion improved the reliability of themultilayer ceramic capacitor.

Next, eighteen multilayer ceramic capacitors were prepared for TestExamples 1-6 to 1-9 shown in Table 2, in addition to Test Example 1-1.In Test Example 1-6, Sn as an additive was further added to the thirddielectric ceramic layer in the same amount as that added to the firstdielectric ceramic layer and the second dielectric ceramic layer in TestExample 1-2. In Test Examples 1-7 to 1-9, the amount of Sn added to thethird dielectric ceramic layer was gradually larger than that in TestExamples 1-6. In Test Example 1-1, Sn was not added to the thirddielectric ceramic layer.

For Test Examples 1-1 and 1-6 to 1-9, MTTF was determined in the samemanner as in Test Examples 1-1 to 1-5. The results are shown in Table 2.

TABLE 2 Sn Sn Sn CONCENTRATION CONCENTRATION CONCENTRATION OF FIRSTALLOY OF SECOND ALLOY OF THIRD ALLOY PORTION (at %) PORTION (at %)PORTION (at %) MTTF (hr) EVALUATION TEST 1 0 0 15.3 FAIL EXAMPLE1- 1TEST 1 1 1 22 GOOD EXAMPLE1- 6 TEST 1 1.1 1.2 25 GOOD EXAMPLE1- 7 TEST 11.3 1.3 27 GOOD EXAMPLE1- 8 TEST 1 1.4 1.4 41 EXCELLENT EXAMPLE1- 9

According to Table 2, it is confirmed that, since the third alloyportion together with the second alloy portion was provided, MTTF isbeyond the prescribed time of about 15.3 hours, and thus it wasevaluated as good, and it is further found that MTTF was better as theSn concentration was higher. On the other hand, in Test Example 1-1 inwhich the second alloy portion and the third alloy portion including Snwere not provided, MTTF could not exceed the prescribed time. Thus, itwas confirmed that the second alloy portion and the third alloy portionimproved the reliability of the multilayer ceramic capacitor.

(2) Average Particle Size of the Dielectric Particles included NearIntersection Region

FIG. 19 shows a plane including the length (L) direction and the width(W) direction of the multilayer ceramic capacitor 1 of the presentpreferred embodiment, and a plane including the second dielectricceramic layer 20 b and the second internal electrode layer 22. As shownin FIG. 19, both sides of the end closer to the first end surface 15 inthe multilayer ceramic capacitor 1 in the width (W) direction eachinclude an intersection 400 of the interface surrounded by the seconddielectric ceramic layer 20 b, the second internal electrode layer 22,and the third dielectric ceramic layers 41 and 42. This intersection 400is an intersection of the interface 2220 b between the second dielectricceramic layer 20 b and the second internal electrode layer 22, and aninner surface 401 in the width (W) direction in the third dielectricceramic layers 41 and 42. Furthermore, similarly to this, both sidescloser to the second end surface 16 in the width (W) direction eachinclude the intersection 400 of the interface surrounded by the seconddielectric ceramic layer 20 b, the first internal electrode layer 21,and the third dielectric ceramic layers 41 and 42.

An inner region of a circle 400 r having a radius of about 5 μm, forexample, around the intersection 400 is defined as a second nearintersection region 420. An inner region of the circle 400 r having aradius of about 5 μm around the intersection 400 is defined as a thirdnear intersection region 430. The region inside the circle 400 r alsoincludes the line of the circle 400 r. In the following description, thesecond near intersection region 420 close to the second dielectricceramic layer 20 b, and a third near intersection region 430 close tothe third dielectric ceramic layers 41 and 42 may be collectivelyreferred to as a near intersection region 440. The inner region of thesecond near intersection region 420 includes a portion of the seconddielectric ceramic layer 20 b. The inner region of the third nearintersection region 430 includes a portion of the third dielectricceramic layers 41 and 42.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, (A) the average particle size of the dielectric particlesincluded in each near intersection region 440 is preferably smaller thanthe average particle size of the dielectric particles included in thefirst dielectric ceramic layer 20 a, the dielectric particles includedin the second dielectric ceramic layer 20 b, and the dielectricparticles included in the third dielectric ceramic layers 41 and 42.

In addition, in the multilayer ceramic capacitor 1 of the presentpreferred embodiment, (B) it is preferable for the ratio of the averageparticle size of the dielectric particles included in each nearintersection region 440 smaller than the average particle size of thedielectric particles included therein to be about 5% or more smaller,for example.

It should be noted that the average particle size of the dielectricparticles included in the second dielectric ceramic layer 20 b in thiscase refers to an average particle size of the dielectric particlesincluded in the second dielectric ceramic layer 20 b in a portion otherthan the second near intersection region 420, and the average particlesize of the dielectric particles included in the third dielectricceramic layers 41 and 42 refers to an average particle size of thedielectric particles included in the third dielectric ceramic layers 41and 42 in a portion other than the third near intersection region 430.

The multilayer ceramic capacitor 1 of the present preferred embodimenthaving the above configuration (A) or (B) preferably further has any ofthe following configurations of (C) to (I).

(C) The difference between the average particle size of the dielectricparticles included in the second dielectric ceramic layer 20 b and theaverage particle size of the dielectric particles included in the thirddielectric ceramic layers 41 and 42 is within about 5%, for example; theaverage particle size of the dielectric particles included in the firstdielectric ceramic layer 20 a is larger than the average particle sizeof the dielectric particles included in the second dielectric ceramiclayer 20 b and the average particle size of the dielectric particlesincluded in the third dielectric ceramic layers 41 and 42; and theaverage particle size of the dielectric particles included in the nearintersection region 440 is smaller than the average particle size of thedielectric particles included in the second dielectric ceramic layer 20b and the average particle size of the dielectric particles included inthe third dielectric ceramic layers 41 and 42.

(D) The difference between the average particle size of the dielectricparticles included in the first dielectric ceramic layer 20 a and theaverage particle size of the dielectric particles included in the seconddielectric ceramic layer 20 b is within about 5%, for example; theaverage particle size of the dielectric particles included in the thirddielectric ceramic layer 41 and 42 is smaller than the average particlesize of the dielectric particles included in the first dielectricceramic layer 20 a and the average particle size of the dielectricparticles included in the second dielectric ceramic layer 20 b; and theaverage particle size of the dielectric particles included in the nearintersection region 440 is smaller than the average particle size of thedielectric particles included in the third dielectric ceramic layers 41and 42.

(E) The difference between the average particle size of the dielectricparticles included in the first dielectric ceramic layer 20 a and theaverage particle size of the dielectric particles included in the thirddielectric ceramic layer 41 and 42 is within about 5%, for example; theaverage particle size of the dielectric particles included in the seconddielectric ceramic layer 20 b smaller than the average particle size ofthe dielectric particles included in the first dielectric ceramic layer20 a and the average particle size of the dielectric particles includedin the third dielectric ceramic layer 41 and 42; and the averageparticle size of the dielectric particles included in the nearintersection region 440 is smaller than the average particle size of thedielectric particles included in the second dielectric ceramic layer 20b.

(F) The difference between the average particle size of the dielectricparticles included in the first dielectric ceramic layer 20 a and theaverage particle size of the dielectric particles included in the seconddielectric ceramic layer 20 b is within about 5%, for example; thedifference between the average particle size of the dielectric particlesincluded in the first dielectric ceramic layer 20 a and the averageparticle size of the dielectric particles included in the thirddielectric ceramic layers 41 and 42 is within about 5%, for example; andthe difference between the average particle size of the dielectricparticles included in the second dielectric ceramic layer 20 b and theaverage particle size of the dielectric particles included in the thirddielectric ceramic layers 41 and 42 is within about 5%, for example, andthe average particle size of the dielectric particles included in thenear intersection region 440 is smaller than the average particle sizeof the dielectric particles included in the first dielectric ceramiclayer 20 a, the average particle size of the dielectric particlesincluded in the second dielectric ceramic layer 20 b, and the averageparticle size of the dielectric particles included in the thirddielectric ceramic layers 41 and 42.

(G) The average particle size of the dielectric particles included inthe first dielectric ceramic layer 20 a is smaller than the averageparticle size of the dielectric particles included in the seconddielectric ceramic layer 20 b; the average particle size of thedielectric particles included in the third dielectric ceramic layer 41and 42 is smaller than the average particle size of the dielectricparticles included in the first dielectric ceramic layer 20 a; and theaverage particle size of the dielectric particles included in the nearintersection region 440 is smaller than the average particle size of thedielectric particles included in the third dielectric ceramic layers 41and 42.

(H) The average particle size of the dielectric particles included inthe first dielectric ceramic layer 20 a is smaller than the averageparticle size of the dielectric particles included in the thirddielectric ceramic layer 41 and 42; the average particle size of thedielectric particles included in the second dielectric ceramic layer 20b is smaller than the average particle size of the dielectric particlesincluded in the first dielectric ceramic layer 20 a; and the averageparticle size of the dielectric particles included in the nearintersection region 440 is smaller than the average particle size of thedielectric particles included in the second dielectric ceramic layer 20b.

(I) The average particle size of the dielectric particles included inthe near intersection region 440 is smaller than the average particlesize of the dielectric particles included in the first dielectricceramic layer 20 a; and the average particle size of the dielectricparticles included in the third dielectric ceramic layers 41 and 42 orthe average particle size of the dielectric particles included in thesecond dielectric ceramic layer 20 b is smaller than the averageparticle size of the dielectric particles included in the nearintersection region 440.

It is possible to control the average particle size of the dielectricparticles included in the first dielectric ceramic layer 20 a, thesecond dielectric ceramic layer 20 b, and the third dielectric ceramiclayer 41 and 42 by adjusting the amount of sintering aid such as Si, Mn,etc., for example, included in the dielectric ceramic slurry formingeach dielectric ceramic layer, and further adjusting the firingtemperature.

As described above, in the multilayer ceramic capacitor 1 of the presentpreferred embodiment, the average particle size of the dielectricparticles included in the near intersection region 440 is smaller thanthe average particle size of the dielectric particles included in thefirst dielectric ceramic layer 20 a and the dielectric particlesincluded in the second dielectric ceramic layer 20 b around the nearintersection region 440, and the average particle size of the dielectricparticles included in the third dielectric ceramic layer 41 and 42.

The electric field is likely to be concentrated in the near intersectionregion 440, and the occurrence of the electric field concentration maydegrade the reliability of a multilayer ceramic capacitor. However, inthe multilayer ceramic capacitor 1 of the present preferred embodiment,the average particle size of the dielectric particles included in thenear intersection region 440 is smaller than the average particle sizeof the dielectric particles included in each of the first dielectricceramic layer 20 a, the second dielectric ceramic layer 20 b, and thethird dielectric ceramic layers 41 and 42 therearound. Thus, since theaverage particle size is small, electric field concentration is reducedor prevented by the presence of many grain boundaries. As a result, itis possible to improve the reliability of a multilayer ceramiccapacitor.

Test Example 2

Next, Test Example 2 will be described which verifies that it issuperior in that the multilayer ceramic capacitor 1 of the presentpreferred embodiment having the average particle size of the dielectricparticles included in the near intersection region 440 which is smallerthan the average particle size of the dielectric particles included ineach of the first dielectric ceramic layer 20 a and the third dielectricceramic layers 41 and 42 therearound.

The average particle sizes of the dielectric particles included in eachof the first dielectric ceramic layer, the second dielectric ceramiclayer, and the third dielectric ceramic layer are measured as follows.

Average Particle Size of the Dielectric Particles Included in the FirstDielectric Ceramic Layer

In the non-limiting example of a manufacturing method for the multilayerceramic capacitor of the present preferred embodiment described above,the multilayer body 10 obtained by firing the green chip 110 withoutcofiring the first external electrode 51 and the second externalelectrode 52 is polished from the first end surface 15 side or thesecond end surface 16 side, to obtain a polished body leaving thecentral portion in the length (L) direction as a test body, as shown inFIG. 20. As shown in FIG. 20, in the central portion of the width (W)direction, an imaginary line OS1 orthogonal or substantially orthogonalto the width (W) direction was assumed. Furthermore, the region in whichthe first dielectric ceramic layer 20 a in relation to the acquisitionof the capacitance of the polished body, and the first internalelectrode layer 21 and the second internal electrode layer 22 arestacked was equally divided into three regions along the imaginary lineOS1 in the stacking direction. The three regions include an upper regionF1, a center region F2, and a lower region F3. For each of the regionsF1, F2, and F3, the first dielectric ceramic layer 20 a was imaged witha field size of about 4.3 μm×about 3.2 μm, and for each of the regionsF1, F2, and F3, the area was measured by image processing for 20 piecesof dielectric particles. Then, the equivalent circle diameter wascalculated from the measured area and averaged to obtain the averageparticle size. The average particle size was measured in each of theupper region F1, the center region F2, and the lower region F3, and nosignificant difference was found in the measured values. Therefore, theaverage particle size of the center region F2 is regarded as the averageparticle size of the first dielectric ceramic layer.

Average Particle Size of the Dielectric Particles included in the ThirdDielectric Ceramic Layer

In the test body shown in FIG. 20, an imaginary line is assumed whichconnects the ends of the plurality of first internal electrode layers 21and the plurality of second internal electrode layers 22 closer to thefirst side surface 13 or the second side surface 14 in the stacking (T)direction. FIG. 20 shows an imaginary line OS3 which connects the endsof the plurality of first internal electrode layers 21 and the pluralityof second internal electrode layers 22 close to the second side surface14 in the stacking (T) direction. As shown in FIG. 21, the thirddielectric ceramic layer 42 was imaged from the virtual line OS3 at afield size about 4.3 μm×about 3.2 μm in the range of about 5 μm on thethird dielectric ceramic layer 42 side, and for each of the regions F1,F2, and F3, the area was measured by image processing for 20 pieces ofdielectric particles. The reference numeral 42F in FIG. 21 indicates animaging region. Then, the equivalent circle diameter was calculated fromthe measured area and averaged to obtain the average particle size. Theaverage particle size was measured in each of the upper region F1, thecenter region F2, and the lower region F3, and no significant differencewas found in the measured values. Therefore, the average particle sizeof the center region F2 is regarded as the average particle size of thethird dielectric ceramic layer.

Average Particle Size of the Dielectric Particles included in the SecondDielectric Ceramic Layer

The multilayer body 10 is polished from the first end surface 15 side orthe second end surface 16 side, until just before at least one internalelectrode layer is exposed. For example, as shown in FIG. 22, polishingis performed from the second end surface 16 side to a surface Jimmediately before the second internal electrode layer 22 appears. Asshown in FIG. 23, in the central portion in the width (W) direction, animaginary line OS2 perpendicular or substantially perpendicular to thewidth (W) direction was assumed. Then, along the imaginary line OS2, thesecond dielectric ceramic layer 20 b was divided into three equalportions of an upper region G1, a center region G2, and a lower regionG3 in the stacking direction. For each of the regions G1, G2, and G3,the second dielectric ceramic layer was imaged with a field size ofabout 4.3 μm×about 3.2 μm, and for each of the regions G1, G2 and G3,the area was measured by image processing for 20 pieces of dielectricparticles. Then, the equivalent circle diameter was calculated from themeasured area and averaged to obtain the average particle size. Theaverage particle size was measured in each of the upper region G1, thecenter region G2, and the lower region G3, and no significant differencewas found in the measured values. Therefore, the average particle sizeof the center region G2 is regarded as the average particle size of thesecond dielectric ceramic layer.

Average Particle Size of Dielectric Particles included in the NearIntersection Region

In the test body shown in FIG. 23, an imaginary line OS4 is assumedwhich connects the ends of the plurality of first internal electrodelayers 21 and the plurality of second internal electrode layers 22closer to the second side surface 14 in the stacking (T) direction.Then, along the imaginary line OS4, the region on both sides in thewidth (W) direction of the imaginary line OS4 including the nearintersection region 440 was divided into three equal regions in thestacking direction. The three equal region includes an upper region H1,a center region H2, and a lower region H3. As shown in FIG. 24, thesecond dielectric ceramic layer 20 b and the third dielectric ceramiclayer 42 were imaged in a field size of about 4.3 μm×about 3.2 μm in therange of 5 μm in the width (W) direction on both sides of the virtualline OS4, and for each of the regions F1, F2, and F3, the area wasmeasured by image processing for 20 pieces of dielectric particles.Reference numeral 42H in FIG. 24 indicates an imaging region. Then, theequivalent circle diameter was calculated from the measured area andaveraged to obtain the average particle size. The average particle sizewas measured in each of the upper region H1, the center region H2, andthe lower region H3, and no significant difference was found in themeasured values. Therefore, the average particle size of the centerregion H2 is regarded as the average particle size of the nearintersection region 440.

Test Examples 2-1 to 2-24 shown in Table 3 were prepared as themultilayer ceramic capacitors corresponding to (C) to (I) describedabove. Furthermore, for Test Examples 2-25 to 2-27, the average particlesize of the dielectric particles included in the near intersectionregion 440 was larger than the average particle size of the dielectricparticles included in the first dielectric ceramic layer 20 a, theaverage particle size of the dielectric particles included in the seconddielectric ceramic layer 20 b, and the average particle size of thedielectric particles included in the third dielectric ceramic layers 41and 42. The average particle sizes of Test Examples 2-1 to 2-27 wereexamined by the measurement method described above.

In Table 3, “first” in the item of comparison of the average particlesize refers to the average particle size of the dielectric particlesincluded in the first dielectric ceramic layer; “second” refers to theaverage particle size of the dielectric particles included in the seconddielectric ceramic layer; “third” refers to the average particle size ofthe dielectric particles included in the third dielectric ceramic layer;and “intersection” refers to the average particle size of the dielectricparticles included in the near intersection region.

On the other hand, for the multilayer ceramic capacitors of the TestExamples 2-25 to 2-27, the determination was performed by measuring theresistance value (kΩ) in a state in which voltage of about 6.3 V wasapplied in an environment with a room temperature of about 150° C., toexamine MTTF (mean failure time). MTTF was determined when theresistance value became about 10 kΩ or less, and if MTTF was about 15.3hours (hr) or less, it was evaluated as fail, if MTTF was up to about 30hours beyond about 15.3 hours (hr), it is evaluated as good, and if MTTFwas beyond about 30 hours, it was evaluated as excellent. The resultsare listed in Table 3. It should be noted that, when the coverage of theinternal electrode layer is less than about 80%, since the capacitanceis difficult to be measured, it was evaluated as unmeasurable.

TABLE 3 AVERAGE AVERAGE AVERAGE PARTICLE PARTICLE PARTICLE SIZE OF SIZEOF SIZE OF FIRST SECOND THIRD DIELECTRIC DIELECTRIC DIELECTRIC OMPARISONOF AVERAGE CERAMIC CERAMIC CERAMIC INTER MTTF PARTICLE DIAMETER TESTEXAMPLE LAYER (μm) LAYER (μm) LAYER (μm) SECTION (hr) EVALUATION (C)FIRST > SECOND = TEST 0.42 0.32 0.33 0.15 32.1 EXCELLENT THIRD >INTERSECTION EXAMPLE 2-1  (C) FIRST > SECOND = TEST 0.65 0.33 0.32 0.1333.9 EXCELLENT THIRD > INTERSECTION EXAMPLE 2-2  (C) FIRST > SECOND =TEST 0.71 0.31 0.33 0.14 33.1 EXCELLENT THIRD > INTERSECTION EXAMPLE2-3  (D) FIRST = SECOND > TEST 0.42 0.41 0.32 0.12 34.1 EXCELLENTTHIRD > INTERSECTION EXAMPLE 2-4  (D) FIRST = SECOND > TEST 0.65 0.660.33 0.11 35.2 EXCELLENT THIRD > INTERSECTION EXAMPLE 2-5  (D) FIRST =SECOND > TEST 0.71 0.72 0.35 0.13 33.8 EXCELLENT THIRD > INTERSECTIONEXAMPLE 2-6  (E) FIRST = THIRD > TEST 0.42 0.32 0.41 0.15 32.1 EXCELLENTSECOND > INTERSECTION EXAMPLE 2-7  (E) FIRST = THIRD > TEST 0.65 0.330.66 0.11 35.1 EXCELLENT SECOND > INTERSECTION EXAMPLE 2-8  (E) FIRST =THIRD > TEST 0.71 0.35 0.72 0.14 33.1 EXCELLENT SECOND > INTERSECTIONEXAMPLE 2-9  (F) FIRST = SECOND = TEST 0.42 0.43 0.42 0.11 35.6EXCELLENT THIRD > INTERSECTION EXAMPLE 2-10 (F) FIRST = SECOND = TEST0.65 0.66 0.64 0.13 22.9 EXCELLENT THIRD > INTERSECTION EXAMPLE 2-11 (F)FIRST = SECOND = TEST 0.71 0.72 0.71 0.12 34.0 EXCELLENT THIRD >INTERSECTION EXAMPLE 2-12 (G) SECOND > FIRST > TEST 0.42 0.51 0.35 0.1532.1 EXCELLENT THIRD > INTERSECTION EXAMPLE 2-13 (G) SECOND > FIRST >TEST 0.65 0.73 0.57 0.16 31.6 EXCELLENT THIRD > INTERSECTION EXAMPLE2-14 (G) SECOND > FIRST > TEST 0.71 0.85 0.66 0.13 33.7 EXCELLENTTHIRD > INTERSECTION EXAMPLE 2-15 (E) THIRD = FIRST > TEST 0.42 0.320.43 0.14 33.1 EXCELLENT SECOND > INTERSECTION EXAMPLE 2-16 (E) THIRD =FIRST > TEST 0.65 0.56 0.66 0.12 34.2 EXCELLENT SECOND > INTERSECTIONEXAMPLE 2-17 (E) THIRD = FIRST > TEST 0.71 0.65 0.72 0.13 33.8 EXCELLENTSECOND > INTERSECTION EXAMPLE 2-18 (H) THIRD > FIRST > TEST 0.52 0.420.33 0.16 31.6 EXCELLENT SECOND > INTERSECTION EXAMPLE 2-19 (H) THIRD >FIRST > TEST 0.72 0.66 0.62 0.12 34.3 EXCELLENT SECOND > INTERSECTIONEXAMPLE 2-20 (H) THIRD > FIRST > TEST 0.86 0.7 0.75 0.14 33.1 EXCELLENTSECOND > INTERSECTION EXAMPLE 2-21 (I) FIRST > TEST 0.41 0.31 0.25 0.2427.6 GOOD INTERSECTION > SECOND EXAMPLE 2-22 or THIRD (I) FIRST > TEST0.65 0.45 0.32 0.33 14.6 FAIL INTERSECTION > SECOND EXAMPLE 2-23 orTHIRD (I) FIRST > TEST 0.73 0.55 0.44 0.43 13.1 FAIL INTERSECTION >SECOND EXAMPLE 2-24 or THIRD INTERSECTION > THIRD = TEST 0.42 0.41 0.420.91 9.1 FAIL FIRST = SECOND EXAMPLE 2-25 INTERSECTION > THIRD = TEST0.52 0.51 0.51 0.9 8.9 FAIL FIRST = SECOND EXAMPLE 2-26 INTERSECTION >THIRD = TEST 0.71 0.72 0.71 0.9 8.7 FAIL FIRST = SECOND EXAMPLE 2-27

According to Table 3, it is confirmed that, when the average particlesize of the dielectric particles included in the near intersectionregion was smaller than the average particle size of the dielectricparticles included in each of the first dielectric ceramic layer, thesecond dielectric ceramic layer, and the third dielectric ceramic layer,MTTF was increased, which improved the reliability of the multilayerceramic capacitor.

(3) Method for Manufacturing with the Addition of a Step of Removing theSide Surface of the Multilayer Body

In a non-limiting example of a method for manufacturing the multilayerceramic capacitor 1 of the present preferred embodiment described above,in order to obtain the green chip 110 which is the unfired multilayerbody 10, the method includes the steps of: printing the unfired firstinternal electrode layer 121 and second internal electrode layer 122 onthe unfired first dielectric ceramic layer 120 a; forming the unfiredsecond dielectric ceramic layer 120 b in a region other than the regionof the first dielectric ceramic layer 120 a where the first internalelectrode layer 121 and the second internal electrode layer 122 areprinted; stacking the plurality of first dielectric ceramic layer 120 ato form the green chip 110; exposing, by cutting the mother block 104,the first internal electrode layer 121 and the second internal electrodelayer 122, the first dielectric ceramic layer 120 a, and the seconddielectric ceramic layer 120 b from the first side surface 113 and thesecond side surface 114 of the individual green chips 110; and bondingthe unfired third dielectric ceramic layer (the side margin portions 41and 42) to the first side surface 113 and the second side surface 114 ofthe individual green chips 110. Here, the green chip 110 is an exampleof a multilayer body. The first dielectric ceramic layer 120 a is anexample of a dielectric layer. The first internal electrode layer 121and the second internal electrode layer 122 are examples of internalelectrode patterns. The second dielectric ceramic layer 120 b is anexample of a dielectric pattern. The first side surface 113 and thesecond side surface 114 are examples of side surfaces. The side marginportions 41 and 42 which are the unfired third dielectric ceramic layerare examples of a dielectric gap layer.

In this manufacturing method, it is possible to add a step of removing acertain thickness of the first side surface 113 and the second sidesurface 114 after the step of exposing, by cutting the mother block 104,the first internal electrode layer 121 and the second internal electrodelayer 122, the first dielectric ceramic layer 120 a, and the seconddielectric ceramic layer 120 b from the first side surface 113 and thesecond side surface 114 of the green chips 110; and before the step ofbonding the third dielectric ceramic layer to the first side surface 113and the second side surface 114 of the green chips 110. Thus, the sidesurfaces of the first dielectric ceramic layer 120 a, the seconddielectric ceramic layer 120 b, and the first internal electrode layer121 and the second internal electrode layer 122 exposed on the firstside surface 113 and the second side surface 114 are removed.

FIG. 25 shows a state in which the first side surface 113 and the secondside surface 114 of the green chip 110 are flattened by removing acertain thickness (for example, about 1 μm or less) therefrom. In FIG.25, the diagram on the left side shows before the step of removing, andthe diagram on the right side shows after the step of removing. Whenobtaining the plurality of green chips 110 by cutting the mother block104, the side surfaces of the first side surface 113 and second sidesurface 114 of the green chip 110 may be slightly bent downward, andthus, plastically deformed due to the stress applied to the lower sidein the drawing which is a cutting direction, as shown in FIG. 25. Inaddition, the cut surface may not be sufficiently smooth, or foreignmatter may exist in the cut surface. For this reason, the thickness tothe extent that the deformed portion is eliminated is removed. Althoughthe method for removing the first side surface 113 and the second sidesurface 114 is not limited, for example, polishing by an appropriatepolishing method, for example, is preferably used.

As shown in FIG. 26, the first side surface 113 and the second sidesurface 114 after the step of removing are formed to be smooth surfacesfrom which foreign matter is removed. The third dielectric ceramic layer(the side margin portions 41 and 42) is bonded to the first side surface113 and the second side surface 114 after the step of removing.

In preferred embodiments of the present invention, each of the seconddielectric ceramic layer 20 b, and the first internal electrode layer 21and the second internal electrode layer 22 may include a resin. Theresin can be included in the material by being added at the time ofmanufacturing. That is, the resin is included in the dielectric paste inthe second dielectric ceramic layer 20 b, and the resin is included inthe conductive paste in the first internal electrode layer 21 and thesecond internal electrode layer 22.

The resin included in the dielectric paste and the conductive paste isadded for the purpose of defining and functioning as a binder, improvingviscosity of the material, and the like. Examples of such resins includepolyvinyl acetal resins, such as polyvinyl butyral and polyvinylacetoacetal, polyvinyl alcohol-based resins, such as polyvinyl alcohol,cellulosic resins such as methylcellulose, ethylcellulose, and cellulosephthalate acetate, (meth)acrylic resins, such as (meth)acrylic acidesters, imide resins such as polyamideimide and polyimide,ethylene-based resins, such as polyethylene oxide, nitrile resins, suchas polyacrylonitrile and polymetallilonitrile, urethane resins, such aspolyurethane, vinyl resins, such as polyethylene, polypropylene, andvinyl acetate, and rubber-based resins, such as styrene-butadienerubber. However, the present invention is not limited thereto.

As the content of the resin, the content included in the seconddielectric ceramic layer 20 b and the content included in the firstdielectric ceramic layer 20 a are preferably different from one another.The resin contents of the first dielectric ceramic layer 20 a and thesecond dielectric ceramic layer 20 b are preferably about 30 wt % ormore and about 50 wt % or less, for example. The resin contents of thefirst dielectric ceramic layer and the second dielectric ceramic layer20 b are preferably different from each other in this range.

In a non-limiting example of a method for manufacturing a multilayerceramic capacitor according to a preferred embodiment of the presentinvention, the thickness of the first dielectric ceramic layer 120 a ispreferably about 0.4 μm or more and about 0.8 μm or less, for example.In a non-limiting example of a method for manufacturing a multilayerceramic capacitor according to a preferred embodiment of the presentinvention, the thickness of the first internal electrode layer 121 andthe second internal electrode layer 122 is preferably about 0.4 μm ormore and about 0.8 μm or less, for example.

Furthermore, in forming the green chip 110, a portion of the secondinternal electrode layer 122 may overlap with a portion of the firstinternal electrode layer 121 and a portion of the second internalelectrode layer 122. More specifically, the ends of the seconddielectric ceramic layer 120 b, and the first internal electrode layer121 and the second internal electrode layer 122 adjacent to each otherin the length (L) direction may be superimposed on each other. Forexample, as shown in FIG. 27, in the length (L) direction, the end ofthe second dielectric ceramic layer 120 b may be superimposed on the endof the first internal electrode layer 121. Similarly to this, an end ofthe second dielectric ceramic layer 120 b may be superimposed on an endof the second internal electrode layer 122. In the configuration inwhich the ends of the length (L) direction are superimposed on eachother, the end of the first internal electrode layer 121 and the end ofthe second dielectric ceramic layer 120 b may be superimposed on the endof the second dielectric ceramic layer 120 b.

A non-limiting example of a method for manufacturing a multilayerceramic capacitor according to a preferred embodiment of the presentinvention includes removing a certain thickness of the first sidesurface 113 and the second side surface 114 of the green chip 110 whichis the unfired multilayer body 10, following by pasting the unfiredthird dielectric ceramic layer to the first side surface 113 and thesecond side surface 114. Thus, it is possible to form the unfired thirddielectric ceramic layer with respect to the first side surface 113 andthe second side surface 114 in a smooth and clean state.

In the non-limiting example of a method for manufacturing a multilayerceramic capacitor according to a preferred embodiment of the presentinvention, by removing the first side surface 113 and the second sidesurface 114 by polishing, it is possible to remove the first sidesurface 113 and the second side surface 114 easily and accurately by aremoval amount with a predetermined thickness.

In a non-limiting example of a method for manufacturing a multilayerceramic capacitor according to a preferred embodiment of the presentinvention, the second dielectric ceramic layer 120 b includes a resin,and the amount of the resin is preferably larger than the amount of theresin included in the first internal electrode layer 121 and the secondinternal electrode layer 122. Thus, the viscosity of the seconddielectric ceramic layer 120 b is relatively increased, and it ispossible to reduce or prevent the occurrence of defects, such as cracksand chips, in the cut surface of the second dielectric ceramic layer 20b when cutting the mother block 104.

In addition, in a non-limiting example of a method for manufacturing amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention, the thickness of the first dielectric ceramic layer120 a is preferably about 0.4 μm or more and about 0.8 μm or less, forexample, and the thickness of the first internal electrode layer 121 andthe second internal electrode layer 122 is preferably about 0.4 μm ormore and about 0.8 μm or less, for example. By the unfired dielectriclayer and the internal electrode layer having such a thickness, it ispossible to allow the first dielectric ceramic layer 20 a, the firstinternal electrode layer 21, and the second internal electrode layer 22after firing to be formed to have a suitable thickness.

Moreover, a non-limiting example of a method for manufacturing amultilayer ceramic capacitor according to a preferred embodiment of thepresent invention, a portion of the second internal electrode layer 122may overlap the first internal electrode layer 121 and the secondinternal electrode layer 122. Thus, after firing, it is possible to formthe second dielectric ceramic layer 20 b with a sufficient thicknesswithout any gap.

(4) Defect Portion in the Second Dielectric Ceramic Layer

In the multilayer ceramic capacitor 1 of the present preferredembodiment, as shown in FIGS. 28 and 29, there is a defect portion 520provided by being partially missing in the second dielectric ceramiclayer 20 b between at least one second dielectric ceramic layer 20 b andone third dielectric ceramic layer 42. Furthermore, similarly to this,there is a defect portion 520 provided by being partially missing in thesecond dielectric ceramic layer 20 b between the at least one seconddielectric ceramic layer 20 b and the other third dielectric ceramiclayer 41.

In the region where the second dielectric ceramic layer 20 b isdisposed, i.e. in at least one of the region between the end of thefirst internal electrode layer 21 which is not connected to the secondexternal electrode 52 and the second external electrode 52 and theregion between the end of the second internal electrode layer 22 whichis not connected to the first external electrode 51 and the firstexternal electrode 51 in the length (L) direction of the multilayer body10, the defect portion 520 is included between the first dielectricceramic layers 20 a at the position in the stacking (T) direction on theplane including the stacking (T) direction and the width (W) direction,and is included between the second dielectric ceramic layer 20 b and thethird dielectric ceramic layer 41 or 42 at the position in the width (W)direction.

When fabricating the green chip 110 which is the unfired multilayer body10, the side surface of the unfired second dielectric ceramic layer 120b is subjected to processing followed by firing, to obtain themultilayer body 10 having the defect portion 520 on the side surface ofthe second dielectric ceramic layer 20 b. Any method can be used as theprocessing method for obtaining the defective portion 520, and forexample, the defect portion 520 can be formed by drilling with asuitable tool or the like.

Furthermore, in “Method for manufacturing with the addition of a step ofremoving the side surface of the multilayer body” described above, whenthe first side surface 113 or the second side surface 114 of the unfiredgreen chip 110 is removed by polishing or the like, a portion of theside surface of the second dielectric ceramic layer 20 b may be missing,and a fine hole may be formed. If such a hole occurs, the hole may be adefect portion 520. The defect portion 520 may not be formed on the sidesurface of all the second internal electrode layer 22, and it sufficesif one or more of the defect portions 520 is formed on each of the firstside surface 13 side and the second side surface 14 side at both ends ofthe length (L) direction.

Furthermore, as shown in FIGS. 28 and 29, a segregation 530 of Si may bedisposed in the defect portion 520. The segregation 530 of Si is asegregation of Si added to the second dielectric ceramic layer 20 b asan additive.

The size of the segregation 530 of Si when viewed in the diameter of theequivalent circle diameter is preferably, for example, larger than about⅓ of the thickness of the second dielectric ceramic layer 20 b.Furthermore, the size may preferably be about 100 nm or more and about600 nm or less, for example.

The defect portion 520 is preferably disposed close to the firstinternal electrode layer 21 or the second internal electrode layer 22.In FIG. 29, the defect portion 520 is disposed close to the end of thesecond internal electrode layer 22 in the length (L) direction.Similarly to this, the defect portion 520 is preferably disposed closeto the end of the first internal electrode layer 21 in the length (L)direction.

The dimension of the segregation 530 of Si is preferably about 0.1% ormore and about 5% or less, for example, of the dimensions of the thirddielectric ceramic layers 41 and 42 in the width (W) direction.

In the region where the second dielectric ceramic layer 20 b isdisposed, i.e. in at least one region in the length (L) direction of themultilayer body 10 between the end of the first internal electrode layer21 which is not connected to the second external electrode 52 and thesecond external electrode 52 and the region between the end of thesecond internal electrode layer 22 which is not connected to the firstexternal electrode 51 and the first external electrode 51, themultilayer ceramic capacitor 1 includes the defect portion 520 which isbetween the first dielectric ceramic layers 20 a at the position in thestacking (T) direction on the plane including the stacking (T) directionand the width (W) direction, and is between the second dielectricceramic layer 20 b and the third dielectric ceramic layer 41 or 42 atthe position in the width (W) direction.

Thus, it is possible to alleviate the stress generated in the seconddielectric ceramic layer 20 b at the time of firing by the defectportion 520. As a result, it is possible to reduce or prevent crackingor chipping from occurring in the second dielectric ceramic layer 20 b.

In the multilayer ceramic capacitor 1, the segregation 530 of Si may bedisposed at the defect portion 520. If the segregation 530 exists in thedefect portion 520, entry of moisture is reduced or prevented by thesegregation 530. Due to the segregation 530 being present in the defectportion 520, the humidity resistance of the multilayer ceramic capacitor1 is improved. The segregation 530 may be present in all of the defectportions 520 or may be present in a portion of the defect portion 520.With the defect portion 520 in which the segregation 530 is present, itis possible to reduce or prevent cracking or chipping from occurring inthe second dielectric ceramic layer 20 b, and the humidity resistance ofthe multilayer ceramic capacitor 1 can be improved.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the segregation 530 of Si is preferably about ⅓ or more (orless than about ⅓) of the thickness of the second dielectric ceramiclayer 20 b.

In the multilayer ceramic capacitor 1, the defect portion 520 isdisposed close to the first internal electrode layer 21 and the secondinternal electrode layer 22. The region close to the first internalelectrode layer 21 and the second internal electrode layer 22 receives arelatively large stress generated at the time of firing. However, thestress is alleviated by the defect portion 520, and as a result of whichthe occurrence of cracking or chipping can be effectively reduced orprevented.

In the multilayer ceramic capacitor 1, in the width direction, thedimension of the segregation 530 of Si is preferably about 0.1% or moreand about 5% or less, for example, of the dimensions of the thirddielectric ceramic layers 41 and 42. When the segregation 530 of Si ispresent in the defect portion 520, it is possible to effectively reduceor prevent the occurrence of cracking and chipping, and it is alsopossible to improve the humidity resistance of the multilayer ceramiccapacitor 1.

(5) Segregation at the End of the Internal Electrode Layer Side of theSecond Dielectric Ceramic Layer

As shown in FIG. 30, in the multilayer ceramic capacitor 1 of thepresent preferred embodiment, a first segregation 610 may be present atthe end in the length (L) direction of the first internal electrodelayer 21 which is not connected to the second external electrode 52. Inaddition, the first segregation 610 may be present at the end in thelength (L) direction of the second internal electrode layer 22 which isnot connected to the first external electrode 51.

As shown in FIG. 31, the first segregation 610 is generated due to ametal element 610 a originating from the second dielectric ceramic layer20 b being segregated in a layered structure. Examples of the metalelement 610 a include at least one among Mg, Mn, and Si. The segregation610 due to the metal element 610 a occurs when the metal elementincluded in the second dielectric ceramic layer 20 b migrates to thefirst internal electrode layer 21 and the second internal electrodelayer 22 during firing of the second dielectric ceramic layer 20 b.

On the other hand, as shown in FIG. 32, a second segregation 620 may bepresent at the end of the first internal electrode layer 21 in the width(W) direction. Furthermore, the second segregation 620 may be present atthe end of the second internal electrode layer 22 in the width (W)direction.

The second segregation 620 is generated due to a metal element 620 aoriginating from the third dielectric ceramic layers 41 and 42 incontact with the first internal electrode layer 21 and the secondinternal electrode layer 22 being segregated in a layered form.Similarly to the first segregation 610, examples of the metal element620 a include at least one among Mg, Mn, and Si. The segregation 620 dueto the metal element 620 a is generated is due to the metal elementincluded in the third dielectric ceramic layers 41 and 42 migrating tothe first internal electrode layer 21 and the second internal electrodelayer 22 during firing of the third dielectric ceramic layers 41 and 42.

In the multilayer ceramic capacitor 1, the first segregation 610segregated in the first internal electrode layer 21, the firstsegregation 610 segregated in the second internal electrode layer 22,the second segregation 620 segregated in the first internal electrodelayer 21, and the second segregation 620 segregated in the secondinternal electrode layer 22 are preferably different from one another inthe metal element included in at least one set of segregations therein.

When the first dielectric ceramic layer 20 a includes BaTiO₃ as a maincomponent, the content of the metal element included in the firstsegregation 610 with respect to the first internal electrode layer 21and the second internal electrode layer 22 is preferably, for example,about 0.3 mol % or more with respect to 100 moles of Ti. Similarly tothis, the content of the metal element included in the secondsegregation 620 with respect to the first internal electrode layer 21and the second internal electrode layer 22 is preferably, for example,about 0.3 mol % or more with respect to 100 moles of Ti.

In a preferred embodiment of the present invention, the length along thelength (L) direction of the region in which the first segregation 610 ispresent in the first internal electrode layer 21 is preferably about 0.1μm or more, for example. Furthermore, the length along the length (L)direction of the region in which the first segregation 610 is present inthe second internal electrode layer 22 is preferably about 0.1 μm ormore, for example. Furthermore, the length along the width (W) directionof the region in which the second segregation 620 is present in thefirst internal electrode layer 21 is preferably about 0.1 μm or more,for example. Furthermore, the length along the width (W) direction inthe region in which the second segregation 620 is present in the secondinternal electrode layer 22 is preferably about 0.1 μm or more, forexample. By having these lengths, electric field concentration can bereduced or prevented, and thus it is possible to reliably obtain theadvantageous effect of improving the reliability.

With regard to the length of the first segregation 610 and the secondsegregation 620, when a length becomes below the above length, it isdifficult to reduce the electric field concentration. Furthermore, inthe first segregation 610, if it exceeds about 0.5% of the length (L)direction, or in the second segregation 620, if it exceeds about 1.0% ofthe width (W) direction, the metal element to be segregated (at leastone of Mg, Mn, and Si, for example) becomes excessive, and the functionof storing the charge of the internal electrode layer is degraded.

The length of the first segregation 610 in the length (L) direction canbe controlled by adjusting the content of the metal element 610 aincluded in the second dielectric ceramic layer 20 b and migrating tothe first internal electrode layer 21 and the second internal electrodelayer 22 to be segregated. Furthermore, the length of the secondsegregation 620 in the width (W) direction can be controlled byadjusting the content of the metal element 620 a included in the thirddielectric ceramic layers 41 and 42, and migrating to the first internalelectrode layer 21 and the second internal electrode layer 22 to besegregated.

In the multilayer ceramic capacitor 1, the first segregation 610 by atleast one metal element selected from the group consisting of Mg, Mn,and Si, for example, is present in each of the end in the length (L)direction which is not connected to the second external electrode 52 inthe first internal electrode layer 21, and the end in the length (L)direction which is not connected to the first external electrode 51 inthe second internal electrode layer 22.

The electric field is likely to be concentrated at the end in the length(L) direction of each of the first internal electrode layer 21 and thesecond internal electrode layer 22 in contact with the second dielectricceramic layer 20 b, and when the electric field concentration occurs,the reliability of a multilayer ceramic capacitor may be reduced.However, in the multilayer ceramic capacitor 1 of the present preferredembodiment, the electric field concentration is reduced or prevented bythe first segregation 610, and thus it is possible to improve thereliability.

In the multilayer ceramic capacitor 1, the second segregation 620 by atleast one metal element selected from the group consisting of Mg, Mn,and Si, for example, is present in each of the end in the width (W)direction of the first internal electrode layer 21, and the end in thewidth (W) direction of the second internal electrode layer 22.

The electric field is likely to be concentrated at the end in the width(W) direction of each of the first internal electrode layer 21 and thesecond internal electrode layer 22 in contact with the third dielectricceramic layers 41 and 42, and when the electric field concentrationoccurs, the reliability of a multilayer ceramic capacitor may bereduced. However, in the multilayer ceramic capacitor 1 of the presentpreferred embodiment, since the electric field concentration is reducedor prevented by the second segregation 620, it is possible to improvethe reliability.

In the multilayer ceramic capacitor 1, the first segregation 610segregated in the first internal electrode layer 21, the firstsegregation 610 segregated in the second internal electrode layer 22,the second segregation 620 segregated in the first internal electrodelayer 21, and the second segregation 620 segregated in the secondinternal electrode layer 22 are different from one another in the metalelement included in at least one set of segregations therein.

As a result, it is possible to provide an optimal metal elementaccording to the position where the first segregation 610 and the secondsegregation 620 are provided, and thus it is possible to improvereliability.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the first dielectric ceramic layer 20 a includes Ba and Ti,and the content of each of the metal element 610 a included in the firstsegregation 610 and the metal element 620 a included in the secondsegregation 620 with respect to the internal electrode layer ispreferably about 0.3 mol % or more, for example, with respect to 100moles of Ti.

Thus, the electric field concentration described above can beeffectively reduced or prevented, and the reliability can be furtherimproved.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the region where the first segregation 610 is present in thefirst internal electrode layer 21 is preferably about 0.3 μm or more,for example, in the length (L) direction; the region where the firstsegregation 610 is present in the second internal electrode layer 22 ispreferably about 0.3 μm or more, for example, in the length (L)direction; the region where the second segregation 620 is present in thefirst segregation 610 is preferably about 0.3 μm or more, for example,in the width (W) direction; and the region where the second segregation620 is present in the second segregation 620 is preferably about 0.3 μmor more, for example, in the width (W) direction.

Thus, the electric field concentration is reduced or prevented by thesegregation, and thus the advantageous effect of improving thereliability is reliably obtained.

Test Example 3

Next, Test Example 3 will be described which verifies the advantageouseffects of the first segregation 610 and the second segregation 620 inthe multilayer ceramic capacitor 1 of the present preferred embodiment.

As shown in Table 4, Test Examples 3-1 to 3-18 were prepared for themultilayer ceramic capacitor including the second dielectric ceramiclayer 20 b including any one of the elements of Mg, Mn, Si and the thirddielectric ceramic layers 41 and 42. Then, for each Test Example, theconcentration of the element, and the length in the length (L) directionand the length in the width (W) direction of the first segregationgenerated at the end in the length (L) direction of the first internalelectrode layer 21 and the second internal electrode layer 22 wereexamined. The concentrations of the metal elements of the firstsegregation and the second segregation were examined by using the samemethod as for the concentration of the second alloy portion and theconcentration of the third alloy portion in “Test Example 1” describedabove. Furthermore, the length of each of the first segregation and thesecond segregation was measured by EDX analysis.

For the multilayer ceramic capacitors of Test Examples 3-1 to 3-18, thedetermination was performed by measuring, after being cooled to roomtemperature after being heated for about 1 hour in an environment with aroom temperature of about 150° C., the resistance value (kΩ) in a statein which a voltage of about 6.3 V was applied, to examine MTTF (meanfailure time). In addition, whether or not the capacitance was reducedwas examined by an LCR meter (E4980 available from KeysightTechnologies). When the decrease in the capacitance was about 3% ormore, or MTTF was about 15.3 hours or less, it was evaluated as fail,when the decrease of the capacitance was less than about 3%, and MTTFwas more than about 15.3 hours and less than about 30 hours, it wasevaluated as good, and when the decrease in the capacitance was lessthan about 3% and MTTF was more than about 30 hours, it was evaluated asexcellent. The results are listed in Table 4.

TABLE 4 LENGTH IN LENGTH IN LENGTH WIDTH CONCENTRATION DIRECTIONDIRECTION CAPACITANCE ELEMENT (MOLE %) (μm) (μm) MTTF (hr) DECREASEEVALUATION TEST Si 0.2 0.08 0.07 14.1  0.1% FAIL EXAMPLE DECREASED 3-1TEST Si 0.3 0.1 0.12 29.7 0.13% GOOD EXAMPLE DECREASED 3-2 TEST Si 0.50.3 0.27 30.8 0.38% EXCELLENT EXAMPLE DECREASED 3-3 TEST Si 0.55 0.40.34 31.5 0.45% EXCELLENT EXAMPLE DECREASED 3-4 TEST Si 0.6 0.45 0.4232.3  0.5% EXCELLENT EXAMPLE DECREASED 3-5 TEST Si 0.7 2.1 3.2 38.9 3.5% FAIL EXAMPLE DECREASED 3-6 TEST Mg 0.2 0.07 0.05 13.5 0.11% FAILEXAMPLE DECREASED 3-7 TEST Mg 0.3 0.1 0.13 29.7 0.13% GOOD EXAMPLEDECREASED 3-8 TEST Mg 0.5 0.3 0.29 30.8 0.38% EXCELLENT EXAMPLEDECREASED 3-9 TEST Mg 0.55 0.4 0.42 31.5 0.45% EXCELLENT EXAMPLEDECREASED 3-10 TEST Mg 0.6 0.45 0.51 32.3  0.5% EXCELLENT EXAMPLEDECREASED 3-11 TEST Mg 0.7 2.3 3.0 38.9  3.2% FAIL EXAMPLE DECREASED3-12 TEST Mn 0.2 0.07 0.02 14.9 0.15% FAIL EXAMPLE DECREASED 3-13 TESTMn 0.3 0.1 0.05 29.7 0.13% GOOD EXAMPLE DECREASED 3-14 TEST Mn 0.5 0.30.26 30.8 0.38% EXCELLENT EXAMPLE DECREASED 3-15 TEST Mn 0.55 0.4 0.4231.5 0.45% EXCELLENT EXAMPLE DECREASED 3-16 TEST Mn 0.6 0.45 0.42 32.3 0.5% EXCELLENT EXAMPLE DECREASED 3-17 TEST Mn 0.7 1.9 2.5 33.5  3.2%FAIL EXAMPLE DECREASED 3-18

By allowing the second dielectric layer to include Mg, Mn, and Si, so asto produce a segregated portion at the end in the length direction andthe width direction of the internal electrode, it is possible toeliminate the reliability degradation factor which is likely to occur atthe end thereof. However, if the content is too large, the region whichdefines and functions as a metal of the internal electrode becomesnarrow, resulting in a decrease in capacitance.

(6) Segregation Formed in the Corner Region of the Internal ElectrodeLayer Side of the Second Dielectric Ceramic Layer

When the first segregation 610 and the second segregation 620 describedabove are included, a third segregation 630 is preferably present asshown in FIG. 33. The third segregation 630 is present in each of afirst corner region 710 and a second corner region 720.

The first corner region 710 is a region in which the length (L)direction in which the first segregation 610 exists overlaps the width(W) direction in which the second segregation 620 exists, in the firstinternal electrode layer 21. Furthermore, the second corner region 720is a region in which the length (L) direction in which the firstsegregation 610 exists overlaps the width (W) direction in which thesecond segregation 620 exists, in the second internal electrode layer22. The third segregation 630 is generated by the segregation of themetal element 610 a of the first segregation 610 and the metal element620 a of the second segregation 620.

In a preferred embodiment of the present invention, it is preferable forthe metal element 610 a included in the first segregation 610 and themetal element 620 a included in the second segregation 620 to bedifferent from each other, and the metal element 630 a of the thirdsegregation 630 include both the metal element 610 a included in thefirst segregation 610 and the metal element 620 a included in the secondsegregation 620.

Furthermore, in a preferred embodiment of the present invention, theregion where the first segregation 610 exists is preferably about 0.1 μmor more, for example, in the length (L) direction, and the region wherethe second segregation 620 exists is preferably about 0.1 μm or more,for example, in the width (W) direction.

FIG. 33 shows a plane including the length (L) direction and the width(W) direction in the multilayer ceramic capacitor 1. The thirdsegregation 630 is preferably segregated in a substantially right-angledtriangular shape so that the region where the third segregation 630exists becomes larger as approaching the end in the length (L) directionin the plane including the length (L) direction and the width (W)direction. A portion or all of the third segregation 630 is included inthe near intersection region 440 in FIG. 19.

Furthermore, in the multilayer ceramic capacitor 1, it is preferable forthe second dielectric ceramic layer 20 b to be arranged with respect tothe first internal electrode layer 21 and the second internal electrodelayer 22 so that a portion thereof is superimposed on the region wherethe third segregation 630 exists in the stacking (T) direction. Morespecifically, for example, as shown in FIG. 34, the end of the seconddielectric ceramic layer 20 b is superimposed, in the length (L)direction, on the end of the second internal electrode layer 22 in theregion including the third segregation 630. Similarly to this, the endof the second dielectric ceramic layer 20 b may be superimposed on theend of the first internal electrode layer 21. In such a mode in whichthe end in the length (L) direction is superimposed thereon, the end ofthe first internal electrode layer 21 or the end of the seconddielectric ceramic layer 20 b may be superimposed on the end of thesecond dielectric ceramic layer 20 b.

In the multilayer ceramic capacitor 1, the first segregation 610 by atleast one metal element selected from the group consisting of Mg, Mn,and Si is present in each of the end of the first internal electrodelayer 21 in the length (L) direction which is not connected to thesecond external electrode 52, and the end of the second internalelectrode layer 22 in the length (L) direction which is not connected tothe first external electrode 51; the second segregation 620 by at leastone metal element selected from the group consisting of Mg, Mn, and Siis present in each of the end of the first internal electrode layer 21in the width (W) direction, and the end of the second internal electrodelayer 22 in the width (W) direction; and the third segregation 630 bythe respective metal elements of the first segregation 610 and secondsegregation 620 is present in each of the first corner region 710 wherethe end in the length (L) direction in which the first segregation 610exists in the first internal electrode layer 21 overlaps the width (W)direction in which the second segregation 620 exists in the firstinternal electrode layer 21, and the second corner region 720 where theend in the length (L) direction in which the first segregation 610exists in the second internal electrode layer 22 overlaps the width (W)direction in which the second segregation 620 exists.

The electric field is likely to be concentrated at the first cornerregion 710 and the second corner region 720, and when the electric fieldconcentration occurs, the reliability of a multilayer ceramic capacitormay be degraded. However, in the multilayer ceramic capacitor 1 of thepresent preferred embodiment, since the electric field concentration tothe first corner region 710 and the second corner region 720 is reducedor prevented by the third segregation 630, the reliability can beimproved.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the metal element 610 a included in the first segregation610 and the metal element 620 a included in the second segregation 620are different from each other, and the metal element included in thethird segregation 630 includes both the metal element 610 a included inthe first segregation 610 and the metal element 620 a included in thesecond segregation 620.

As a result, it is possible for the third segregation 630 to reduce orprevent the electric field concentration to the first corner region 710and the second corner region 720, thus improving the reliability.

It should be noted that, in the third segregation 630, Mg is preferablyused as the metal element disposed on the side close to the thirddielectric ceramic layers 41 and 42. On the other hand, in the thirdsegregation 630, Si is preferably used as the metal element disposed onthe side close to the second dielectric ceramic layer 20 b, from theviewpoint of the possibility of improving moisture resistance.Therefore, it is preferable for both Mg and Si to be segregated in thefirst corner region 710 and the second corner region 720. In addition,there is a possibility that the short-circuit recovery is performed dueto the first segregation 610 at the ends in the width (W) direction ofthe first internal electrode layer 21 and the second internal electrodelayer 22. Furthermore, it is more preferable for Sn to be a solidsolution in the first internal electrode layer 21 and the secondinternal electrode layer 22.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, preferably, the region where the first segregation 610exists is about 0.1 μm or more in the length (L) direction, and theregion where the second segregation 620 exists is about 0.1 μm or morein the width (W) direction, for example. Thus, the electric fieldconcentration is reduced or prevented by segregation, and theadvantageous effect of improving the reliability is reliably obtained.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the region where the third segregation 630 exists becomeslarger approaching the end in the length (L) direction in a planeincluding the length (L) direction and the width (W) direction.

Thus, the area of the third segregation 630 in the portion of the end ofthe second dielectric ceramic layer 20 b in the length (L) directionwhere the electric field concentration is likely to occur increases, andreduction or prevention of the electric field concentration by the thirdsegregation 630 is achieved more effectively, thus making it possible tofurther improve the reliability.

In the multilayer ceramic capacitor 1 of the present preferredembodiment, the second dielectric ceramic layer 20 b is arranged withrespect to the first internal electrode layer 21 and the second internalelectrode layer 22 so that a portion thereof is superimposed on theregion where the third segregation 630 exists in the stacking (T)direction.

Thus, the region where the third segregation 630 exists is likely tobecome larger approaching the end in the length (L) direction in theplane including the length (L) direction and the width (W) direction.

Test Example 4

Next, Test Example 4 will be described which verifies the advantageouseffects of the third segregation 630 in the multilayer ceramic capacitor1.

As shown in Table 5, Test Examples 4-1 to 4-18 were prepared for themultilayer ceramic capacitors each including the second dielectricceramic layer including any one of the metal elements of Mg, Mn, and Si,and the third dielectric ceramic layer including any one of Mg, Mn, andSi. Then, the concentration of the metal element included in the thirdsegregation occurring in the first corner region and the second cornerregion of each of the multilayer ceramic capacitor, the length of thelength (L) direction and the length of the width (W) direction wereexamined. The concentration of the metal element of the thirdsegregation was examined by using the same method as the concentrationof the second alloy portion and the concentration of the third alloyportion in “Test Example 1” described above. Also, the respectivelengths of the third segregation were measured by EDX analysis.

For the multilayer ceramic capacitors of Test Examples 4-1 to 4-14, thedetermination was performed by measuring the resistance value (kΩ) in astate in which a voltage of about 6.3 V was applied in an environmentwith a room temperature of about 150° C., to examine MTTF (mean failuretime). MTTF was determined when the resistance value became about 10 kΩor less, and if MTTF was about 15.3 hours (hr) or less, it was evaluatedas fail, if MTTF was up to about 30 hours beyond about 15.3 hours (hr),it is evaluated as good, and if MTTF was beyond about 30 hours, it wasevaluated as excellent. The results are listed in Table 5. In addition,whether or not the capacitance was reduced was examined by an LCR meter(E4980 available from Keysight Technologies), and those showing thereduction of capacitance of about 3% or more were evaluated as fail. Itshould be noted that, when the coverage of the internal electrode layeris less than about 80%, since the capacitance is difficult to bemeasured, it was evaluated as unmeasurable.

TABLE 5 SEGREGATION SEGREGATION LENGTH IN CONCENTRATION LENGTH IN WIDTHLENGTH MTTF ELEMENT (MOLE %) DIRECTION DIRECTION (μm) (hr) EVALUATIONTEST EXAMPLE Si 0.2 0.07 0.05 15.2 FAIL 4-1 TEST EXAMPLE Si 0.3 0.1 0.127.3 GOOD 4-2 TEST EXAMPLE Si 0.5 1.1 1.1 32.1 EXCELLENT 4-3 TESTEXAMPLE Si 0.55 1.3 1.3 33.4 EXCELLENT 4-4 TEST EXAMPLE Si 0.6 1.5 1.535.6 EXCELLENT 4-5 TEST EXAMPLE Si 0.7 2.12 2.12 38.9 FAIL 4-6CAPACITANCE DECREASED 3% TEST EXAMPLE Mg 0.2 0.08 0.07 14.8 FAIL 4-7TEST EXAMPLE Mg 0.3 0.1 0.1 27.3 GOOD 4-8 TEST EXAMPLE Mg 0.5 1.1 1.132.1 EXCELLENT 4-9 TEST EXAMPLE Mg 0.55 1.3 1.3 33.4 EXCELLENT 4-10 TESTEXAMPLE Mg 0.6 1.5 1.5 35.6 EXCELLENT 4-11 TEST EXAMPLE Mg 0.7 2.11 2.1138.9 FAIL 4-12 CAPACITANCE DECREASED 3% TEST EXAMPLE Mn 0.2 0.06 0.0713.5 FAIL 4-13 TEST EXAMPLE Mn 0.3 0.1 0.1 27.3 GOOD 4-14 TEST EXAMPLEMn 0.5 1.1 1.1 32.1 EXCELLENT 4-15 TEST EXAMPLE Mn 0.55 1.3 1.3 33.4EXCELLENT 4-16 TEST EXAMPLE Mn 0.6 1.5 1.5 35.6 EXCELLENT 4-17 TESTEXAMPLE Mn 0.7 1.7 1.6 42.5 FAIL 4-18 CAPACITANCE DECREASED 3%

By allowing the second ceramic dielectric layer and the third ceramicdielectric layer to include Si, Mg, and Mn, it is possible to producemany segregation regions in the corners. In particular, electric fieldconcentration occurs in the corner, which tends to degrade thereliability. However, it is possible to improve the reliability byproducing a segregated region. However, if the content is too large, theregion which functions as a metal of the internal electrode becomesnarrow, resulting in a reduction in capacitance.

(7) Thickness of the Second Dielectric Ceramic Layer

FIG. 35 schematically shows the WT cross-section at the central portionin the length (L) direction of the multilayer body 10 in the multilayerceramic capacitor 1, and respectively shows, in this cross-section, thethickness of the first dielectric ceramic layer 20 a as T1 and thethickness at the end in the width (W) direction as T2.

Furthermore, FIG. 36 shows a portion of the LT cross-section of themultilayer ceramic capacitor 1 of the present preferred embodiment, andT3 refers to the thickness of the second dielectric ceramic layer 20 b.Although FIG. 36 shows the second dielectric ceramic layer 20 b incontact with the second internal electrode layer 22, the thickness ofthe second dielectric ceramic layer 20 b in contact with the firstinternal electrode layer 21 is also regarded as T3. In other words, thethickness T3 of the second dielectric ceramic layer 20 b refers to eachof the thicknesses between the end of the first internal electrode layer21 in the length (L) direction which is not connected to the secondexternal electrode 52, and the second external electrode 52, and betweenthe end of the second internal electrode layer 22 in the length (L)direction which is not connected to the first external electrode 51 andthe second external electrode 52.

In a preferred embodiment of the present invention, the difference inthickness between T1 and T2 is relatively small and is within about 10%of T1. In contrast, the thickness of T3 is larger than T1 and T2, andthe difference is preferably, for example, about 10% or more of T1 andT2.

The method of increasing the thickness T3 of the second dielectricceramic layer 20 b more than the thicknesses T1 and T2 of the firstdielectric ceramic layer 20 a is not limited to the method describedabove and, for example, a method is also possible by causing the end ofthe unfired second dielectric ceramic layer 120 b in the length (L)direction to be superimposed on the ends of the unfired first internalelectrode layer 121 and the unfired second internal electrode layer 122in the length (L) direction, when fabricating the green chip 110 beforefiring, following which the green chip 110 is fired.

Among T1, T2, and T3, the thickness T1 of the central portion of thefirst dielectric ceramic layer 20 a is preferably about 0.7 μm or less,for example. The thickness T3 of the second dielectric ceramic layer 20b is preferably about 0.4 μm or more, for example.

In the multilayer ceramic capacitor 1, in a plane including the centerportion in the length (L) direction, and the stacking (T) direction andthe width (W) direction of the first dielectric ceramic layer 20 a, whenthe thickness at the center portion in the stacking (T) direction isdefined as T1, the thickness at the end of the first dielectric ceramiclayer 20 a in the width (W) direction is defined as T2, and therespective thicknesses between the end of the first internal electrodelayer 21 in the length (L) direction which is not connected to thesecond external electrode 52, and the second external electrode 52 andbetween the end of the second internal electrode layer 22 in the length(L) direction which is not connected to the first external electrode 51,and the first external electrode 51 is defined as T3, the difference inthickness between T1 and T2 is within 10% of T1, the thickness of T3 isgreater than T1 and T2, and the difference thereof is preferably, forexample, about 10% or more of T1 and T2.

Thus, the element thickness by the second dielectric ceramic layer 20 bdisposed for the purpose of level difference elimination is providedsufficiently between the first dielectric ceramic layer 20 a sandwichingthe first internal electrode layer 21 and the second internal electrodelayer 22, a result of which it is possible to improve the reliability.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer ceramic capacitor comprising: amultilayer body including a dielectric ceramic layer and an internalelectrode layer stacked in a stacking direction; and an externalelectrode connected to the internal electrode layer; wherein themultilayer body includes a first main surface and a second main surfaceon opposite sides in the stacking direction, a first side surface and asecond side surface on opposite sides in a width direction orthogonal orsubstantially orthogonal to the stacking direction, and a first endsurface and a second end surface on opposite sides in a length directionorthogonal or substantially orthogonal to the stacking direction and thewidth direction; the internal electrode layer includes a first internalelectrode layer that extends to the first end surface, and a secondinternal electrode layer that extends to the second end surface; thesecond internal electrode is opposed to the first internal electrodelayer with the dielectric ceramic layer interposed therebetween; theexternal electrode includes a first external electrode that is disposedon the first end surface and is connected to the first internalelectrode layer, and a second external electrode that is disposed on thesecond end surface and is connected to the second internal electrodelayer; the dielectric ceramic layer includes a first dielectric ceramiclayer and a second dielectric ceramic layer; the first dielectricceramic layer is disposed between the first internal electrode layer andthe second internal electrode layer; the second dielectric ceramic layerincludes a region between the first dielectric ceramic layers providedopposite to each other with the internal electrode layer interposedtherebetween, and in which the internal electrode layer is not disposed,and such that a portion of the second dielectric ceramic layer overlapsthe first dielectric ceramic layer in the stacking direction; themultilayer body includes an inner layer portion in which the firstinternal electrode layer and the second internal electrode layer arealternately stacked with the dielectric ceramic layer interposedtherebetween, an outer layer portion sandwiching the inner layer portionin the stacking direction and including a ceramic material, and a thirddielectric ceramic layer sandwiching the inner layer portion and theouter layer portion in the width direction and including a dielectricceramic material; and in at least one of a region between an end of thefirst internal electrode layer which is not connected to the secondexternal electrode and the second external electrode, and a regionbetween an end of the second internal electrode layer which is notconnected to the first external electrode and the first externalelectrode, in the length direction, a defect portion defined by aportion that is partially missing in the second dielectric ceramic layeris provided on a plane including the stacking direction and the widthdirection, such that the defect portion is located between the firstdielectric ceramic layers in the stacking direction and is locatedbetween the second dielectric ceramic layer and the third dielectricceramic layer in the width direction.
 2. The multilayer ceramiccapacitor according to claim 1, wherein a segregation of Si is providedin the defect portion.
 3. The multilayer ceramic capacitor according toclaim 2, wherein the segregation of Si is equal to or larger than about⅓ of a thickness of the second dielectric ceramic layer.
 4. Themultilayer ceramic capacitor according to claim 1, wherein the defectportion is adjacent to or in a vicinity of the internal electrode layer.5. The multilayer ceramic capacitor according to claim 1, wherein adimension of the segregation of Si in the width direction is about 0.1%or more and about 5% or less of a dimension of the third dielectricceramic layer in the width direction.
 6. The multilayer ceramiccapacitor according to claim 1, wherein each of the first externalelectrode and the second external electrode includes a metal and aceramic material.
 7. The multilayer ceramic capacitor according to claim1, wherein each of the first external electrode and the second externalelectrode includes a Ni layer, a first plated layer, and a second platedlayer.
 8. The multilayer ceramic capacitor according to claim 7, whereineach of the first external electrode and the second external electrodefurther includes a Cu layer.
 9. The multilayer ceramic capacitoraccording to claim 1, wherein the outer layer portion includes aplurality of dielectric ceramic layers.
 10. The multilayer ceramiccapacitor according to claim 1, wherein the dielectric ceramic layerincludes ceramic grains.
 11. The multilayer ceramic capacitor accordingto claim 1, wherein a thickness of the outer layer portion is about 15μm or more and about 40 μm or less.
 12. The multilayer ceramic capacitoraccording to claim 1, wherein the first dielectric ceramic layerincludes Mg; the second dielectric ceramic layer includes Sn; and thethird dielectric ceramic layer includes at least one metal elementselected from a group consisting of Mg, Mn, and Si.
 13. The multilayerceramic capacitor according to claim 1, wherein the dielectric ceramiclayer includes a rare earth element in an amount of about 0.2 mol % ormore and about 5 mol % or less with respect to 100 moles of Ti.
 14. Themultilayer ceramic capacitor according to claim 1, wherein thedielectric ceramic layer has a perovskite structure as a main component.15. The multilayer ceramic capacitor according to claim 1, wherein athickness of each of the first internal electrode layer and the secondinternal electrode layer is about 0.25 μm or more and about 0.4 μm orless.
 16. The multilayer ceramic capacitor according to claim 1, whereina thickness of each of the first dielectric ceramic layer and the seconddielectric ceramic layer is about 0.4 μm or more and about 0.55 μm orless.
 17. The multilayer ceramic capacitor according to claim 1, whereinthe first internal electrode layer includes a plurality of firstinterspersed internal electrodes interspersed discontinuously in thelength direction; and the second internal electrode layer includes aplurality of second interspersed internal electrodes intersperseddiscontinuously in the length direction.
 18. The multilayer ceramiccapacitor according to claim 17, wherein each of the plurality of firstinterspersed internal electrodes and each of the plurality of secondinterspersed internal electrodes is provided within the seconddielectric ceramic layer.